Electron Documentation

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About Electron

Electron is an open source library developed by GitHub for building cross-platform desktop applications with HTML, CSS, and JavaScript. Electron accomplishes this by combining Chromium and Node.js into a single runtime and apps can be packaged for Mac, Windows, and Linux.

Electron began in 2013 as the framework on which Atom, GitHub's hackable text editor, would be built. The two were open sourced in the Spring of 2014.

It has since become a popular tool used by open source developers, startups, and established companies. See who is building on Electron.

Read on to learn more about the contributors and releases of Electron or get started building with Electron in the Quick Start Guide.

Core Team and Contributors

Electron is maintained by a team at GitHub as well as a group of active contributors from the community. Some of the contributors are individuals and some work at larger companies who are developing on Electron. We're happy to add frequent contributors to the project as maintainers. Read more about contributing to Electron.

Releases

Electron releases frequently. We release when there are significant bug fixes, new APIs or are updating versions of Chromium or Node.js.

Updating Dependencies

Electron's version of Chromium is usually updated within one or two weeks after a new stable Chromium version is released, depending on the effort involved in the upgrade.

When a new version of Node.js is released, Electron usually waits about a month before upgrading in order to bring in a more stable version.

In Electron, Node.js and Chromium share a single V8 instance—usually the version that Chromium is using. Most of the time this just works but sometimes it means patching Node.js.

Versioning

As of version 2.0 Electron follows semver. For most applications, and using any recent version of npm, running $ npm install electron will do the right thing.

The version update process is detailed explicitly in our Versioning Doc.

LTS

Long term support of older versions of Electron does not currently exist. If your current version of Electron works for you, you can stay on it for as long as you'd like. If you want to make use of new features as they come in you should upgrade to a newer version.

A major update came with version v1.0.0. If you're not yet using this version, you should read more about the v1.0.0 changes.

Core Philosophy

In order to keep Electron small (file size) and sustainable (the spread of dependencies and APIs) the project limits the scope of the core project.

For instance, Electron uses Chromium's rendering library rather than all of Chromium. This makes it easier to upgrade Chromium but also means some browser features found in Google Chrome do not exist in Electron.

New features added to Electron should primarily be native APIs. If a feature can be its own Node.js module, it probably should be. See the Electron tools built by the community.

History

Below are milestones in Electron's history.

📆 🎉
April 2013 Atom Shell is started .
May 2014 Atom Shell is open sourced .
April 2015 Atom Shell is re-named Electron .
May 2016 Electron releases v1.0.0 .
May 2016 Electron apps compatible with Mac App Store .
August 2016 Windows Store support for Electron apps .

Accelerator

Define keyboard shortcuts.

Accelerators are Strings that can contain multiple modifiers and a single key code, combined by the + character, and are used to define keyboard shortcuts throughout your application.

Examples:

  • CommandOrControl+A
  • CommandOrControl+Shift+Z

Shortcuts are registered with the globalShortcut module using the register method, i.e.

const {app, globalShortcut} = require('electron')

app.on('ready', () => {
  // Register a 'CommandOrControl+Y' shortcut listener.
  globalShortcut.register('CommandOrControl+Y', () => {
    // Do stuff when Y and either Command/Control is pressed.
  })
})

Platform notice

On Linux and Windows, the Command key does not have any effect so use CommandOrControl which represents Command on macOS and Control on Linux and Windows to define some accelerators.

Use Alt instead of Option. The Option key only exists on macOS, whereas the Alt key is available on all platforms.

The Super key is mapped to the Windows key on Windows and Linux and Cmd on macOS.

Available modifiers

  • Command (or Cmd for short)
  • Control (or Ctrl for short)
  • CommandOrControl (or CmdOrCtrl for short)
  • Alt
  • Option
  • AltGr
  • Shift
  • Super

Available key codes

  • 0 to 9
  • A to Z
  • F1 to F24
  • Punctuations like ~, !, @, #, $, etc.
  • Plus
  • Space
  • Tab
  • Backspace
  • Delete
  • Insert
  • Return (or Enter as alias)
  • Up, Down, Left and Right
  • Home and End
  • PageUp and PageDown
  • Escape (or Esc for short)
  • VolumeUp, VolumeDown and VolumeMute
  • MediaNextTrack, MediaPreviousTrack, MediaStop and MediaPlayPause
  • PrintScreen

Accessibility

Making accessible applications is important and we're happy to introduce new functionality to Devtron and Spectron that gives developers the opportunity to make their apps better for everyone.


Accessibility concerns in Electron applications are similar to those of websites because they're both ultimately HTML. With Electron apps, however, you can't use the online resources for accessibility audits because your app doesn't have a URL to point the auditor to.

These new features bring those auditing tools to your Electron app. You can choose to add audits to your tests with Spectron or use them within DevTools with Devtron. Read on for a summary of the tools.

Spectron

In the testing framework Spectron, you can now audit each window and <webview> tag in your application. For example:

app.client.auditAccessibility().then(function (audit) {
  if (audit.failed) {
    console.error(audit.message)
  }
})

You can read more about this feature in Spectron's documentation.

Devtron

In Devtron, there is a new accessibility tab which will allow you to audit a page in your app, sort and filter the results.

devtron screenshot

Both of these tools are using the Accessibility Developer Tools library built by Google for Chrome. You can learn more about the accessibility audit rules this library uses on that repository's wiki.

If you know of other great accessibility tools for Electron, add them to the accessibility documentation with a pull request.

Enabling Accessibility

Electron applications keep accessibility disabled by default for performance reasons but there are multiple ways to enable it.

Inside Application

By using app.setAccessibilitySupportEnabled(enabled), you can expose accessibility switch to users in the application preferences. User's system assistive utilities have priority over this setting and will override it.

Assistive Technology

Electron application will enable accessibility automatically when it detects assistive technology (Windows) or VoiceOver (macOS). See Chrome's accessibility documentation for more details.

On macOS, third-party assistive technology can switch accessibility inside Electron applications by setting the attribute AXManualAccessibility programmatically:

CFStringRef kAXManualAccessibility = CFSTR("AXManualAccessibility");

+ (void)enableAccessibility:(BOOL)enable inElectronApplication:(NSRunningApplication *)app
{
    AXUIElementRef appRef = AXUIElementCreateApplication(app.processIdentifier);
    if (appRef == nil)
        return;

    CFBooleanRef value = enable ? kCFBooleanTrue : kCFBooleanFalse;
    AXUIElementSetAttributeValue(appRef, kAXManualAccessibility, value);
    CFRelease(appRef);
}

app

Control your application's event lifecycle.

Process: Main

The following example shows how to quit the application when the last window is closed:

const {app} = require('electron')
app.on('window-all-closed', () => {
  app.quit()
})

Events

The app object emits the following events:

Event: 'will-finish-launching'

Emitted when the application has finished basic startup. On Windows and Linux, the will-finish-launching event is the same as the ready event; on macOS, this event represents the applicationWillFinishLaunching notification of NSApplication. You would usually set up listeners for the open-file and open-url events here, and start the crash reporter and auto updater.

In most cases, you should do everything in the ready event handler.

Event: 'ready'

Returns:

  • launchInfo Object macOS

Emitted when Electron has finished initializing. On macOS, launchInfo holds the userInfo of the NSUserNotification that was used to open the application, if it was launched from Notification Center. You can call app.isReady() to check if this event has already fired.

Event: 'window-all-closed'

Emitted when all windows have been closed.

If you do not subscribe to this event and all windows are closed, the default behavior is to quit the app; however, if you subscribe, you control whether the app quits or not. If the user pressed Cmd + Q, or the developer called app.quit(), Electron will first try to close all the windows and then emit the will-quit event, and in this case the window-all-closed event would not be emitted.

Event: 'before-quit'

Returns:

  • event Event

Emitted before the application starts closing its windows. Calling event.preventDefault() will prevent the default behaviour, which is terminating the application.

Note: If application quit was initiated by autoUpdater.quitAndInstall() then before-quit is emitted after emitting close event on all windows and closing them.

Note: On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.

Event: 'will-quit'

Returns:

  • event Event

Emitted when all windows have been closed and the application will quit. Calling event.preventDefault() will prevent the default behaviour, which is terminating the application.

See the description of the window-all-closed event for the differences between the will-quit and window-all-closed events.

Note: On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.

Event: 'quit'

Returns:

  • event Event
  • exitCode Integer

Emitted when the application is quitting.

Note: On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.

Event: 'open-file' macOS

Returns:

  • event Event
  • path String

Emitted when the user wants to open a file with the application. The open-file event is usually emitted when the application is already open and the OS wants to reuse the application to open the file. open-file is also emitted when a file is dropped onto the dock and the application is not yet running. Make sure to listen for the open-file event very early in your application startup to handle this case (even before the ready event is emitted).

You should call event.preventDefault() if you want to handle this event.

On Windows, you have to parse process.argv (in the main process) to get the filepath.

Event: 'open-url' macOS

Returns:

  • event Event
  • url String

Emitted when the user wants to open a URL with the application. Your application's Info.plist file must define the url scheme within the CFBundleURLTypes key, and set NSPrincipalClass to AtomApplication.

You should call event.preventDefault() if you want to handle this event.

Event: 'activate' macOS

Returns:

  • event Event
  • hasVisibleWindows Boolean

Emitted when the application is activated. Various actions can trigger this event, such as launching the application for the first time, attempting to re-launch the application when it's already running, or clicking on the application's dock or taskbar icon.

Event: 'continue-activity' macOS

Returns:

  • event Event
  • type String - A string identifying the activity. Maps to NSUserActivity.activityType.
  • userInfo Object - Contains app-specific state stored by the activity on another device.

Emitted during Handoff when an activity from a different device wants to be resumed. You should call event.preventDefault() if you want to handle this event.

A user activity can be continued only in an app that has the same developer Team ID as the activity's source app and that supports the activity's type. Supported activity types are specified in the app's Info.plist under the NSUserActivityTypes key.

Event: 'will-continue-activity' macOS

Returns:

Emitted during Handoff before an activity from a different device wants to be resumed. You should call event.preventDefault() if you want to handle this event.

Event: 'continue-activity-error' macOS

Returns:

  • event Event
  • type String - A string identifying the activity. Maps to NSUserActivity.activityType.
  • error String - A string with the error's localized description.

Emitted during Handoff when an activity from a different device fails to be resumed.

Event: 'activity-was-continued' macOS

Returns:

  • event Event
  • type String - A string identifying the activity. Maps to NSUserActivity.activityType.
  • userInfo Object - Contains app-specific state stored by the activity.

Emitted during Handoff after an activity from this device was successfully resumed on another one.

Event: 'update-activity-state' macOS

Returns:

  • event Event
  • type String - A string identifying the activity. Maps to NSUserActivity.activityType.
  • userInfo Object - Contains app-specific state stored by the activity.

Emitted when Handoff is about to be resumed on another device. If you need to update the state to be transferred, you should call event.preventDefault() immediately, construct a new userInfo dictionary and call app.updateCurrentActiviy() in a timely manner. Otherwise the operation will fail and continue-activity-error will be called.

Event: 'new-window-for-tab' macOS

Returns:

  • event Event

Emitted when the user clicks the native macOS new tab button. The new tab button is only visible if the current BrowserWindow has a tabbingIdentifier

Event: 'browser-window-blur'

Returns:

Emitted when a browserWindow gets blurred.

Event: 'browser-window-focus'

Returns:

Emitted when a browserWindow gets focused.

Event: 'browser-window-created'

Returns:

Emitted when a new browserWindow is created.

Event: 'web-contents-created'

Returns:

Emitted when a new webContents is created.

Event: 'certificate-error'

Returns:

  • event Event
  • webContents WebContents
  • url String
  • error String - The error code
  • certificate Certificate
  • callback Function

    • isTrusted Boolean - Whether to consider the certificate as trusted

Emitted when failed to verify the certificate for url, to trust the certificate you should prevent the default behavior with event.preventDefault() and call callback(true).

const {app} = require('electron')

app.on('certificate-error', (event, webContents, url, error, certificate, callback) => {
  if (url === 'https://github.com') {
    // Verification logic.
    event.preventDefault()
    callback(true)
  } else {
    callback(false)
  }
})

Event: 'select-client-certificate'

Returns:

Emitted when a client certificate is requested.

The url corresponds to the navigation entry requesting the client certificate and callback can be called with an entry filtered from the list. Using event.preventDefault() prevents the application from using the first certificate from the store.

const {app} = require('electron')

app.on('select-client-certificate', (event, webContents, url, list, callback) => {
  event.preventDefault()
  callback(list[0])
})

Event: 'login'

Returns:

  • event Event
  • webContents WebContents
  • request Object

    • method String
    • url URL
    • referrer URL
  • authInfo Object

    • isProxy Boolean
    • scheme String
    • host String
    • port Integer
    • realm String
  • callback Function

    • username String
    • password String

Emitted when webContents wants to do basic auth.

The default behavior is to cancel all authentications, to override this you should prevent the default behavior with event.preventDefault() and call callback(username, password) with the credentials.

const {app} = require('electron')

app.on('login', (event, webContents, request, authInfo, callback) => {
  event.preventDefault()
  callback('username', 'secret')
})

Event: 'gpu-process-crashed'

Returns:

  • event Event
  • killed Boolean

Emitted when the gpu process crashes or is killed.

Event: 'accessibility-support-changed' macOS Windows

Returns:

  • event Event
  • accessibilitySupportEnabled Boolean - true when Chrome's accessibility support is enabled, false otherwise.

Emitted when Chrome's accessibility support changes. This event fires when assistive technologies, such as screen readers, are enabled or disabled. See https://www.chromium.org/developers/design-documents/accessibility for more details.

Event: 'session-created'

Returns:

Emitted when Electron has created a new session.

const {app} = require('electron')

app.on('session-created', (event, session) => {
  console.log(session)
})

Event: 'second-instance'

Returns:

  • event Event
  • argv String[] - An array of the second instance's command line arguments
  • workingDirectory String - The second instance's working directory

This event will be emitted inside the primary instance of your application when a second instance has been executed. argv is an Array of the second instance's command line arguments, and workingDirectory is its current working directory. Usually applications respond to this by making their primary window focused and non-minimized.

This event is guaranteed to be emitted after the ready event of app gets emitted.

Methods

The app object has the following methods:

Note: Some methods are only available on specific operating systems and are labeled as such.

app.quit()

Try to close all windows. The before-quit event will be emitted first. If all windows are successfully closed, the will-quit event will be emitted and by default the application will terminate.

This method guarantees that all beforeunload and unload event handlers are correctly executed. It is possible that a window cancels the quitting by returning false in the beforeunload event handler.

app.exit([exitCode])

  • exitCode Integer (optional)

Exits immediately with exitCode. exitCode defaults to 0.

All windows will be closed immediately without asking user and the before-quit and will-quit events will not be emitted.

app.relaunch([options])

  • options Object (optional)

    • args String
    • execPath String (optional)

Relaunches the app when current instance exits.

By default the new instance will use the same working directory and command line arguments with current instance. When args is specified, the args will be passed as command line arguments instead. When execPath is specified, the execPath will be executed for relaunch instead of current app.

Note that this method does not quit the app when executed, you have to call app.quit or app.exit after calling app.relaunch to make the app restart.

When app.relaunch is called for multiple times, multiple instances will be started after current instance exited.

An example of restarting current instance immediately and adding a new command line argument to the new instance:

const {app} = require('electron')

app.relaunch({args: process.argv.slice(1).concat(['--relaunch'])})
app.exit(0)

app.isReady()

Returns Boolean - true if Electron has finished initializing, false otherwise.

app.whenReady()

Returns Promise - fulfilled when Electron is initialized. May be used as a convenient alternative to checking app.isReady() and subscribing to the ready event if the app is not ready yet.

app.focus()

On Linux, focuses on the first visible window. On macOS, makes the application the active app. On Windows, focuses on the application's first window.

app.hide() macOS

Hides all application windows without minimizing them.

app.show() macOS

Shows application windows after they were hidden. Does not automatically focus them.

app.getAppPath()

Returns String - The current application directory.

app.getPath(name)

  • name String

Returns String - A path to a special directory or file associated with name. On failure an Error is thrown.

You can request the following paths by the name:

  • home User's home directory.
  • appData Per-user application data directory, which by default points to:

    • %APPDATA% on Windows
    • $XDG_CONFIG_HOME or ~/.config on Linux
    • ~/Library/Application Support on macOS
  • userData The directory for storing your app's configuration files, which by default it is the appData directory appended with your app's name.
  • temp Temporary directory.
  • exe The current executable file.
  • module The libchromiumcontent library.
  • desktop The current user's Desktop directory.
  • documents Directory for a user's "My Documents".
  • downloads Directory for a user's downloads.
  • music Directory for a user's music.
  • pictures Directory for a user's pictures.
  • videos Directory for a user's videos.
  • logs Directory for your app's log folder.
  • pepperFlashSystemPlugin Full path to the system version of the Pepper Flash plugin.

app.getFileIcon(path[, options], callback)

  • path String
  • options Object (optional)

    • size String

      • small - 16x16
      • normal - 32x32
      • large - 48x48 on Linux, 32x32 on Windows, unsupported on macOS.
  • callback Function

Fetches a path's associated icon.

On Windows, there a 2 kinds of icons:

  • Icons associated with certain file extensions, like .mp3, .png, etc.
  • Icons inside the file itself, like .exe, .dll, .ico.

On Linux and macOS, icons depend on the application associated with file mime type.

app.setPath(name, path)

  • name String
  • path String

Overrides the path to a special directory or file associated with name. If the path specifies a directory that does not exist, the directory will be created by this method. On failure an Error is thrown.

You can only override paths of a name defined in app.getPath.

By default, web pages' cookies and caches will be stored under the userData directory. If you want to change this location, you have to override the userData path before the ready event of the app module is emitted.

app.getVersion()

Returns String - The version of the loaded application. If no version is found in the application's package.json file, the version of the current bundle or executable is returned.

app.getName()

Returns String - The current application's name, which is the name in the application's package.json file.

Usually the name field of package.json is a short lowercased name, according to the npm modules spec. You should usually also specify a productName field, which is your application's full capitalized name, and which will be preferred over name by Electron.

app.setName(name)

  • name String

Overrides the current application's name.

app.getLocale()

Returns String - The current application locale. Possible return values are documented here.

To set the locale, you'll want to use a command line switch at app startup, which may be found here.

Note: When distributing your packaged app, you have to also ship the locales folder.

Note: On Windows you have to call it after the ready events gets emitted.

app.addRecentDocument(path) macOS Windows

  • path String

Adds path to the recent documents list.

This list is managed by the OS. On Windows you can visit the list from the task bar, and on macOS you can visit it from dock menu.

app.clearRecentDocuments() macOS Windows

Clears the recent documents list.

app.setAsDefaultProtocolClient(protocol[, path, args])

  • protocol String - The name of your protocol, without ://. If you want your app to handle electron:// links, call this method with electron as the parameter.
  • path String (optional) Windows - Defaults to process.execPath
  • args String Windows - Defaults to an empty array

Returns Boolean - Whether the call succeeded.

This method sets the current executable as the default handler for a protocol (aka URI scheme). It allows you to integrate your app deeper into the operating system. Once registered, all links with your-protocol:// will be opened with the current executable. The whole link, including protocol, will be passed to your application as a parameter.

On Windows you can provide optional parameters path, the path to your executable, and args, an array of arguments to be passed to your executable when it launches.

Note: On macOS, you can only register protocols that have been added to your app's info.plist, which can not be modified at runtime. You can however change the file with a simple text editor or script during build time. Please refer to Apple's documentation for details.

The API uses the Windows Registry and LSSetDefaultHandlerForURLScheme internally.

app.removeAsDefaultProtocolClient(protocol[, path, args]) macOS Windows

  • protocol String - The name of your protocol, without ://.
  • path String (optional) Windows - Defaults to process.execPath
  • args String Windows - Defaults to an empty array

Returns Boolean - Whether the call succeeded.

This method checks if the current executable as the default handler for a protocol (aka URI scheme). If so, it will remove the app as the default handler.

app.isDefaultProtocolClient(protocol[, path, args])

  • protocol String - The name of your protocol, without ://.
  • path String (optional) Windows - Defaults to process.execPath
  • args String Windows - Defaults to an empty array

Returns Boolean

This method checks if the current executable is the default handler for a protocol (aka URI scheme). If so, it will return true. Otherwise, it will return false.

Note: On macOS, you can use this method to check if the app has been registered as the default protocol handler for a protocol. You can also verify this by checking ~/Library/Preferences/com.apple.LaunchServices.plist on the macOS machine. Please refer to Apple's documentation for details.

The API uses the Windows Registry and LSCopyDefaultHandlerForURLScheme internally.

app.setUserTasks(tasks) Windows

  • tasks Task[] - Array of Task objects

Adds tasks to the Tasks category of the JumpList on Windows.

tasks is an array of Task objects.

Returns Boolean - Whether the call succeeded.

Note: If you'd like to customize the Jump List even more use app.setJumpList(categories) instead.

app.getJumpListSettings() Windows

Returns Object:

  • minItems Integer - The minimum number of items that will be shown in the Jump List (for a more detailed description of this value see the MSDN docs).
  • removedItems JumpListItem[] - Array of JumpListItem objects that correspond to items that the user has explicitly removed from custom categories in the Jump List. These items must not be re-added to the Jump List in the next call to app.setJumpList(), Windows will not display any custom category that contains any of the removed items.

app.setJumpList(categories) Windows

Sets or removes a custom Jump List for the application, and returns one of the following strings:

  • ok - Nothing went wrong.
  • error - One or more errors occurred, enable runtime logging to figure out the likely cause.
  • invalidSeparatorError - An attempt was made to add a separator to a custom category in the Jump List. Separators are only allowed in the standard Tasks category.
  • fileTypeRegistrationError - An attempt was made to add a file link to the Jump List for a file type the app isn't registered to handle.
  • customCategoryAccessDeniedError - Custom categories can't be added to the Jump List due to user privacy or group policy settings.

If categories is null the previously set custom Jump List (if any) will be replaced by the standard Jump List for the app (managed by Windows).

Note: If a JumpListCategory object has neither the type nor the name property set then its type is assumed to be tasks. If the name property is set but the type property is omitted then the type is assumed to be custom.

Note: Users can remove items from custom categories, and Windows will not allow a removed item to be added back into a custom category until after the next successful call to app.setJumpList(categories). Any attempt to re-add a removed item to a custom category earlier than that will result in the entire custom category being omitted from the Jump List. The list of removed items can be obtained using app.getJumpListSettings().

Here's a very simple example of creating a custom Jump List:

const {app} = require('electron')

app.setJumpList([
  {
    type: 'custom',
    name: 'Recent Projects',
    items: [
      { type: 'file', path: 'C:\\Projects\\project1.proj' },
      { type: 'file', path: 'C:\\Projects\\project2.proj' }
    ]
  },
  { // has a name so `type` is assumed to be "custom"
    name: 'Tools',
    items: [
      {
        type: 'task',
        title: 'Tool A',
        program: process.execPath,
        args: '--run-tool-a',
        icon: process.execPath,
        iconIndex: 0,
        description: 'Runs Tool A'
      },
      {
        type: 'task',
        title: 'Tool B',
        program: process.execPath,
        args: '--run-tool-b',
        icon: process.execPath,
        iconIndex: 0,
        description: 'Runs Tool B'
      }
    ]
  },
  { type: 'frequent' },
  { // has no name and no type so `type` is assumed to be "tasks"
    items: [
      {
        type: 'task',
        title: 'New Project',
        program: process.execPath,
        args: '--new-project',
        description: 'Create a new project.'
      },
      { type: 'separator' },
      {
        type: 'task',
        title: 'Recover Project',
        program: process.execPath,
        args: '--recover-project',
        description: 'Recover Project'
      }
    ]
  }
])

app.requestSingleInstanceLock()

Returns Boolean

This method makes your application a Single Instance Application - instead of allowing multiple instances of your app to run, this will ensure that only a single instance of your app is running, and other instances signal this instance and exit.

The return value of this method indicates whether or not this instance of your application successfully obtained the lock. If it failed to obtain the lock you can assume that another instance of your application is already running with the lock and exit immediately.

I.e. This method returns true if your process is the primary instance of your application and your app should continue loading. It returns false if your process should immediately quit as it has sent its parameters to another instance that has already acquired the lock.

On macOS the system enforces single instance automatically when users try to open a second instance of your app in Finder, and the open-file and open-url events will be emitted for that. However when users start your app in command line the system's single instance mechanism will be bypassed and you have to use this method to ensure single instance.

An example of activating the window of primary instance when a second instance starts:

const {app} = require('electron')
let myWindow = null

const gotTheLock = app.requestSingleInstanceLock()

if (!gotTheLock) {
  app.quit()
} else {
  app.on('second-instance', (event, commandLine, workingDirectory) => {
    // Someone tried to run a second instance, we should focus our window.
    if (myWindow) {
      if (myWindow.isMinimized()) myWindow.restore()
      myWindow.focus()
    }
  })

  // Create myWindow, load the rest of the app, etc...
  app.on('ready', () => {
  })
}

app.hasSingleInstanceLock()

Returns Boolean

This method returns whether or not this instance of your app is currently holding the single instance lock. You can request the lock with app.requestSingleInstanceLock() and release with app.releaseSingleInstanceLock()

app.releaseSingleInstanceLock()

Releases all locks that were created by requestSingleInstanceLock. This will allow multiple instances of the application to once again run side by side.

app.setUserActivity(type, userInfo[, webpageURL]) macOS

  • type String - Uniquely identifies the activity. Maps to NSUserActivity.activityType.
  • userInfo Object - App-specific state to store for use by another device.
  • webpageURL String (optional) - The webpage to load in a browser if no suitable app is installed on the resuming device. The scheme must be http or https.

Creates an NSUserActivity and sets it as the current activity. The activity is eligible for Handoff to another device afterward.

app.getCurrentActivityType() macOS

Returns String - The type of the currently running activity.

app.invalidateCurrentActivity() macOS

Invalidates the current Handoff user activity.

app.updateCurrentActivity(type, userInfo) macOS

  • type String - Uniquely identifies the activity. Maps to NSUserActivity.activityType.
  • userInfo Object - App-specific state to store for use by another device.

Updates the current activity if its type matches type, merging the entries from userInfo into its current userInfo dictionary.

app.importCertificate(options, callback) LINUX

  • options Object

    • certificate String - Path for the pkcs12 file.
    • password String - Passphrase for the certificate.
  • callback Function

    • result Integer - Result of import.

Imports the certificate in pkcs12 format into the platform certificate store. callback is called with the result of import operation, a value of 0 indicates success while any other value indicates failure according to chromium net_error_list.

app.disableHardwareAcceleration()

Disables hardware acceleration for current app.

This method can only be called before app is ready.

app.disableDomainBlockingFor3DAPIs()

By default, Chromium disables 3D APIs (e.g. WebGL) until restart on a per domain basis if the GPU processes crashes too frequently. This function disables that behaviour.

This method can only be called before app is ready.

app.getAppMetrics()

Returns ProcessMetric[]: Array of ProcessMetric objects that correspond to memory and cpu usage statistics of all the processes associated with the app.

app.getGPUFeatureStatus()

Returns GPUFeatureStatus - The Graphics Feature Status from chrome://gpu/.

app.setBadgeCount(count) Linux macOS

  • count Integer

Returns Boolean - Whether the call succeeded.

Sets the counter badge for current app. Setting the count to 0 will hide the badge.

On macOS it shows on the dock icon. On Linux it only works for Unity launcher,

Note: Unity launcher requires the existence of a .desktop file to work, for more information please read Desktop Environment Integration.

app.getBadgeCount() Linux macOS

Returns Integer - The current value displayed in the counter badge.

app.isUnityRunning() Linux

Returns Boolean - Whether the current desktop environment is Unity launcher.

app.getLoginItemSettings([options]) macOS Windows

  • options Object (optional)

    • path String (optional) Windows - The executable path to compare against. Defaults to process.execPath.
    • args String Windows - The command-line arguments to compare against. Defaults to an empty array.

If you provided path and args options to app.setLoginItemSettings then you need to pass the same arguments here for openAtLogin to be set correctly.

Returns Object:

  • openAtLogin Boolean - true if the app is set to open at login.
  • openAsHidden Boolean macOS - true if the app is set to open as hidden at login. This setting is not available on MAS builds.
  • wasOpenedAtLogin Boolean macOS - true if the app was opened at login automatically. This setting is not available on MAS builds.
  • wasOpenedAsHidden Boolean macOS - true if the app was opened as a hidden login item. This indicates that the app should not open any windows at startup. This setting is not available on MAS builds.
  • restoreState Boolean macOS - true if the app was opened as a login item that should restore the state from the previous session. This indicates that the app should restore the windows that were open the last time the app was closed. This setting is not available on MAS builds.

app.setLoginItemSettings(settings) macOS Windows

  • settings Object

    • openAtLogin Boolean (optional) - true to open the app at login, false to remove the app as a login item. Defaults to false.
    • openAsHidden Boolean (optional) macOS - true to open the app as hidden. Defaults to false. The user can edit this setting from the System Preferences so app.getLoginItemSettings().wasOpenedAsHidden should be checked when the app is opened to know the current value. This setting is not available on MAS builds.
    • path String (optional) Windows - The executable to launch at login. Defaults to process.execPath.
    • args String Windows - The command-line arguments to pass to the executable. Defaults to an empty array. Take care to wrap paths in quotes.

Set the app's login item settings.

To work with Electron's autoUpdater on Windows, which uses Squirrel, you'll want to set the launch path to Update.exe, and pass arguments that specify your application name. For example:

const appFolder = path.dirname(process.execPath)
const updateExe = path.resolve(appFolder, '..', 'Update.exe')
const exeName = path.basename(process.execPath)

app.setLoginItemSettings({
  openAtLogin: true,
  path: updateExe,
  args: [
    '--processStart', `"${exeName}"`,
    '--process-start-args', `"--hidden"`
  ]
})

app.isAccessibilitySupportEnabled() macOS Windows

Returns Boolean - true if Chrome's accessibility support is enabled, false otherwise. This API will return true if the use of assistive technologies, such as screen readers, has been detected. See https://www.chromium.org/developers/design-documents/accessibility for more details.

app.setAccessibilitySupportEnabled(enabled) macOS Windows

Manually enables Chrome's accessibility support, allowing to expose accessibility switch to users in application settings. https://www.chromium.org/developers/design-documents/accessibility for more details. Disabled by default.

Note: Rendering accessibility tree can significantly affect the performance of your app. It should not be enabled by default.

app.setAboutPanelOptions(options) macOS

  • options Object

    • applicationName String (optional) - The app's name.
    • applicationVersion String (optional) - The app's version.
    • copyright String (optional) - Copyright information.
    • credits String (optional) - Credit information.
    • version String (optional) - The app's build version number.

Set the about panel options. This will override the values defined in the app's .plist file. See the Apple docs for more details.

app.startAccessingSecurityScopedResource(bookmarkData) macOS (mas)

  • bookmarkData String - The base64 encoded security scoped bookmark data returned by the dialog.showOpenDialog or dialog.showSaveDialog methods.

Returns Function - This function must be called once you have finished accessing the security scoped file. If you do not remember to stop accessing the bookmark, kernel resources will be leaked and your app will lose its ability to reach outside the sandbox completely, until your app is restarted.

// Start accessing the file.
const stopAccessingSecurityScopedResource = app.startAccessingSecurityScopedResource(data)
// You can now access the file outside of the sandbox 🎉

// Remember to stop accessing the file once you've finished with it.
stopAccessingSecurityScopedResource()

Start accessing a security scoped resource. With this method electron applications that are packaged for the Mac App Store may reach outside their sandbox to access files chosen by the user. See Apple's documentation for a description of how this system works.

app.commandLine.appendSwitch(switch[, value])

  • switch String - A command-line switch
  • value String (optional) - A value for the given switch

Append a switch (with optional value) to Chromium's command line.

Note: This will not affect process.argv, and is mainly used by developers to control some low-level Chromium behaviors.

app.commandLine.appendArgument(value)

  • value String - The argument to append to the command line

Append an argument to Chromium's command line. The argument will be quoted correctly.

Note: This will not affect process.argv.

app.enableMixedSandbox() Experimental macOS Windows

Enables mixed sandbox mode on the app.

This method can only be called before app is ready.

app.isInApplicationsFolder() macOS

Returns Boolean - Whether the application is currently running from the systems Application folder. Use in combination with app.moveToApplicationsFolder()

app.moveToApplicationsFolder() macOS

Returns Boolean - Whether the move was successful. Please note that if the move is successful your application will quit and relaunch.

No confirmation dialog will be presented by default, if you wish to allow the user to confirm the operation you may do so using the dialog API.

NOTE: This method throws errors if anything other than the user causes the move to fail. For instance if the user cancels the authorization dialog this method returns false. If we fail to perform the copy then this method will throw an error. The message in the error should be informative and tell you exactly what went wrong

app.dock.bounce([type]) macOS

  • type String (optional) - Can be critical or informational. The default is informational

When critical is passed, the dock icon will bounce until either the application becomes active or the request is canceled.

When informational is passed, the dock icon will bounce for one second. However, the request remains active until either the application becomes active or the request is canceled.

Returns Integer an ID representing the request.

app.dock.cancelBounce(id) macOS

  • id Integer

Cancel the bounce of id.

app.dock.downloadFinished(filePath) macOS

  • filePath String

Bounces the Downloads stack if the filePath is inside the Downloads folder.

app.dock.setBadge(text) macOS

  • text String

Sets the string to be displayed in the dock’s badging area.

app.dock.getBadge() macOS

Returns String - The badge string of the dock.

app.dock.hide() macOS

Hides the dock icon.

app.dock.show() macOS

Shows the dock icon.

app.dock.isVisible() macOS

Returns Boolean - Whether the dock icon is visible. The app.dock.show() call is asynchronous so this method might not return true immediately after that call.

app.dock.setMenu(menu) macOS

Sets the application's dock menu.

app.dock.setIcon(image) macOS

Sets the image associated with this dock icon.

app.isPackaged

A Boolean property that returns true if the app is packaged, false otherwise. For many apps, this property can be used to distinguish development and production environments.


Electron App Feedback Program

Electron is working on building a streamlined release process and having faster releases. To help with that, we have the App Feedback Program for large-scale Electron apps to test our beta releases and report app-specific issues to the Electron team. We use this program to help us prioritize work and get applications upgraded to the next stable release as soon as possible. There are a few requirements we expect from participants, such as attending short, online weekly check-ins. If you are interested or have questions, please send us a message at info@electronjs.org.


Electron Application Architecture

Before we can dive into Electron's APIs, we need to discuss the two process types available in Electron. They are fundamentally different and important to understand.

Main and Renderer Processes

In Electron, the process that runs package.json's main script is called the main process. The script that runs in the main process can display a GUI by creating web pages. An Electron app always has one main process, but never more.

Since Electron uses Chromium for displaying web pages, Chromium's multi-process architecture is also used. Each web page in Electron runs in its own process, which is called the renderer process.

In normal browsers, web pages usually run in a sandboxed environment and are not allowed access to native resources. Electron users, however, have the power to use Node.js APIs in web pages allowing lower level operating system interactions.

Differences Between Main Process and Renderer Process

The main process creates web pages by creating BrowserWindow instances. Each BrowserWindow instance runs the web page in its own renderer process. When a BrowserWindow instance is destroyed, the corresponding renderer process is also terminated.

The main process manages all web pages and their corresponding renderer processes. Each renderer process is isolated and only cares about the web page running in it.

In web pages, calling native GUI related APIs is not allowed because managing native GUI resources in web pages is very dangerous and it is easy to leak resources. If you want to perform GUI operations in a web page, the renderer process of the web page must communicate with the main process to request that the main process perform those operations.

Aside: Communication Between Processes

In Electron, we have several ways to communicate between the main process and renderer processes, such as ipcRenderer and ipcMain modules for sending messages, and the remote module for RPC style communication. There is also an FAQ entry on how to share data between web pages.

Using Electron APIs

Electron offers a number of APIs that support the development of a desktop application in both the main process and the renderer process. In both processes, you'd access Electron's APIs by requiring its included module:

const electron = require('electron')

All Electron APIs are assigned a process type. Many of them can only be used from the main process, some of them only from a renderer process, some from both. The documentation for each individual API will state which process it can be used from.

A window in Electron is for instance created using the BrowserWindow class. It is only available in the main process.

// This will work in the main process, but be `undefined` in a
// renderer process:
const { BrowserWindow } = require('electron')

const win = new BrowserWindow()

Since communication between the processes is possible, a renderer process can call upon the main process to perform tasks. Electron comes with a module called remote that exposes APIs usually only available on the main process. In order to create a BrowserWindow from a renderer process, we'd use the remote as a middle-man:

// This will work in a renderer process, but be `undefined` in the
// main process:
const { remote } = require('electron')
const { BrowserWindow } = remote

const win = new BrowserWindow()

Using Node.js APIs

Electron exposes full access to Node.js both in the main and the renderer process. This has two important implications:

1) All APIs available in Node.js are available in Electron. Calling the following code from an Electron app works:

const fs = require('fs')

const root = fs.readdirSync('/')

// This will print all files at the root-level of the disk,
// either '/' or 'C:\'.
console.log(root)

As you might already be able to guess, this has important security implications if you ever attempt to load remote content. You can find more information and guidance on loading remote content in our security documentation.

2) You can use Node.js modules in your application. Pick your favorite npm module. npm offers currently the world's biggest repository of open-source code – the ability to use well-maintained and tested code that used to be reserved for server applications is one of the key features of Electron.

As an example, to use the official AWS SDK in your application, you'd first install it as a dependency:

npm install --save aws-sdk

Then, in your Electron app, require and use the module as if you were building a Node.js application:

// A ready-to-use S3 Client
const S3 = require('aws-sdk/clients/s3')

There is one important caveat: Native Node.js modules (that is, modules that require compilation of native code before they can be used) will need to be compiled to be used with Electron.

The vast majority of Node.js modules are not native. Only 400 out of the ~650.000 modules are native. However, if you do need native modules, please consult this guide on how to recompile them for Electron.


Application Debugging

Whenever your Electron application is not behaving the way you wanted it to, an array of debugging tools might help you find coding errors, performance bottlenecks, or optimization opportunities.

Renderer Process

The most comprehensive tool to debug individual renderer processes is the Chromium Developer Toolset. It is available for all renderer processes, including instances of BrowserWindow, BrowserView, and WebView. You can open them programmatically by calling the openDevTools() API on the webContents of the instance:

const { BrowserWindow } = require('electron')

let win = new BrowserWindow()
win.webContents.openDevTools()

Google offers excellent documentation for their developer tools. We recommend that you make yourself familiar with them - they are usually one of the most powerful utilities in any Electron Developer's tool belt.

Main Process

Debugging the main process is a bit trickier, since you cannot open developer tools for them. The Chromium Developer Tools can be used to debug Electron's main process thanks to a closer collaboration between Google / Chrome and Node.js, but you might encounter oddities like require not being present in the console.

For more information, see the Debugging the Main Process documentation.


Application Distribution

To distribute your app with Electron, you need to download Electron's prebuilt binaries. Next, the folder containing your app should be named app and placed in Electron's resources directory as shown in the following examples. Note that the location of Electron's prebuilt binaries is indicated with electron/ in the examples below.

On macOS:

electron/Electron.app/Contents/Resources/app/
├── package.json
├── main.js
└── index.html

On Windows and Linux:

electron/resources/app
├── package.json
├── main.js
└── index.html

Then execute Electron.app (or electron on Linux, electron.exe on Windows), and Electron will start as your app. The electron directory will then be your distribution to deliver to final users.

Packaging Your App into a File

Apart from shipping your app by copying all of its source files, you can also package your app into an asar archive to avoid exposing your app's source code to users.

To use an asar archive to replace the app folder, you need to rename the archive to app.asar, and put it under Electron's resources directory like below, and Electron will then try to read the archive and start from it.

On macOS:

electron/Electron.app/Contents/Resources/
└── app.asar

On Windows and Linux:

electron/resources/
└── app.asar

More details can be found in Application packaging.

Rebranding with Downloaded Binaries

After bundling your app into Electron, you will want to rebrand Electron before distributing it to users.

Windows

You can rename electron.exe to any name you like, and edit its icon and other information with tools like rcedit.

macOS

You can rename Electron.app to any name you want, and you also have to rename the CFBundleDisplayName, CFBundleIdentifier and CFBundleName fields in the following files:

  • Electron.app/Contents/Info.plist
  • Electron.app/Contents/Frameworks/Electron Helper.app/Contents/Info.plist

You can also rename the helper app to avoid showing Electron Helper in the Activity Monitor, but make sure you have renamed the helper app's executable file's name.

The structure of a renamed app would be like:

MyApp.app/Contents
├── Info.plist
├── MacOS/
│   └── MyApp
└── Frameworks/
    └── MyApp Helper.app
        ├── Info.plist
        └── MacOS/
            └── MyApp Helper

Linux

You can rename the electron executable to any name you like.

Packaging Tools

Apart from packaging your app manually, you can also choose to use third party packaging tools to do the work for you:

Rebranding by Rebuilding Electron from Source

It is also possible to rebrand Electron by changing the product name and building it from source. To do this you need to set the build argument corresponding to the product name (electron_product_name = "YourProductName") in the args.gn file and rebuild.

Creating a Custom Electron Fork

Creating a custom fork of Electron is almost certainly not something you will need to do in order to build your app, even for "Production Level" applications. Using a tool such as electron-packager or electron-forge will allow you to "Rebrand" Electron without having to do these steps.

You need to fork Electron when you have custom C++ code that you have patched directly into Electron, that either cannot be upstreamed, or has been rejected from the official version. As maintainers of Electron, we very much would like to make your scenario work, so please try as hard as you can to get your changes into the official version of Electron, it will be much much easier on you, and we appreciate your help.

Creating a Custom Release with surf-build

  1. Install Surf, via npm: npm install -g surf-build@latest

  2. Create a new S3 bucket and create the following empty directory structure:

    - electron/
      - symbols/
      - dist/
  3. Set the following Environment Variables:

  • ELECTRON_GITHUB_TOKEN - a token that can create releases on GitHub
  • ELECTRON_S3_ACCESS_KEY, ELECTRON_S3_BUCKET, ELECTRON_S3_SECRET_KEY - the place where you'll upload Node.js headers as well as symbols
  • ELECTRON_RELEASE - Set to true and the upload part will run, leave unset and surf-build will do CI-type checks, appropriate to run for every pull request.
  • CI - Set to true or else it will fail
  • GITHUB_TOKEN - set it to the same as ELECTRON_GITHUB_TOKEN
  • SURF_TEMP - set to C:\Temp on Windows to prevent path too long issues
  • TARGET_ARCH - set to ia32 or x64
  1. In script/upload.py, you must set ELECTRON_REPO to your fork (MYORG/electron), especially if you are a contributor to Electron proper.

  2. surf-build -r https://github.com/MYORG/electron -s YOUR_COMMIT -n 'surf-PLATFORM-ARCH'

  3. Wait a very, very long time for the build to complete.


Application Packaging

To mitigate issues around long path names on Windows, slightly speed up require and conceal your source code from cursory inspection, you can choose to package your app into an asar archive with little changes to your source code.

Most users will get this feature for free, since it's supported out of the box by electron-packager, electron-forge, and electron-builder. If you are not using any of these tools, read on.

Generating asar Archives

An asar archive is a simple tar-like format that concatenates files into a single file. Electron can read arbitrary files from it without unpacking the whole file.

Steps to package your app into an asar archive:

1. Install the asar Utility

$ npm install -g asar

2. Package with asar pack

$ asar pack your-app app.asar

Using asar Archives

In Electron there are two sets of APIs: Node APIs provided by Node.js and Web APIs provided by Chromium. Both APIs support reading files from asar archives.

Node API

With special patches in Electron, Node APIs like fs.readFile and require treat asar archives as virtual directories, and the files in it as normal files in the filesystem.

For example, suppose we have an example.asar archive under /path/to:

$ asar list /path/to/example.asar
/app.js
/file.txt
/dir/module.js
/static/index.html
/static/main.css
/static/jquery.min.js

Read a file in the asar archive:

const fs = require('fs')
fs.readFileSync('/path/to/example.asar/file.txt')

List all files under the root of the archive:

const fs = require('fs')
fs.readdirSync('/path/to/example.asar')

Use a module from the archive:

require('/path/to/example.asar/dir/module.js')

You can also display a web page in an asar archive with BrowserWindow:

const { BrowserWindow } = require('electron')
const win = new BrowserWindow()

win.loadURL('file:///path/to/example.asar/static/index.html')

Web API

In a web page, files in an archive can be requested with the file: protocol. Like the Node API, asar archives are treated as directories.

For example, to get a file with $.get:

<script>
let $ = require('./jquery.min.js')
$.get('file:///path/to/example.asar/file.txt', (data) => {
  console.log(data)
})
</script>

Treating an asar Archive as a Normal File

For some cases like verifying the asar archive's checksum, we need to read the content of an asar archive as a file. For this purpose you can use the built-in original-fs module which provides original fs APIs without asar support:

const originalFs = require('original-fs')
originalFs.readFileSync('/path/to/example.asar')

You can also set process.noAsar to true to disable the support for asar in the fs module:

const fs = require('fs')
process.noAsar = true
fs.readFileSync('/path/to/example.asar')

Limitations of the Node API

Even though we tried hard to make asar archives in the Node API work like directories as much as possible, there are still limitations due to the low-level nature of the Node API.

Archives Are Read-only

The archives can not be modified so all Node APIs that can modify files will not work with asar archives.

Working Directory Can Not Be Set to Directories in Archive

Though asar archives are treated as directories, there are no actual directories in the filesystem, so you can never set the working directory to directories in asar archives. Passing them as the cwd option of some APIs will also cause errors.

Extra Unpacking on Some APIs

Most fs APIs can read a file or get a file's information from asar archives without unpacking, but for some APIs that rely on passing the real file path to underlying system calls, Electron will extract the needed file into a temporary file and pass the path of the temporary file to the APIs to make them work. This adds a little overhead for those APIs.

APIs that requires extra unpacking are:

  • child_process.execFile
  • child_process.execFileSync
  • fs.open
  • fs.openSync
  • process.dlopen - Used by require on native modules

Fake Stat Information of fs.stat

The Stats object returned by fs.stat and its friends on files in asar archives is generated by guessing, because those files do not exist on the filesystem. So you should not trust the Stats object except for getting file size and checking file type.

Executing Binaries Inside asar Archive

There are Node APIs that can execute binaries like child_process.exec, child_process.spawn and child_process.execFile, but only execFile is supported to execute binaries inside asar archive.

This is because exec and spawn accept command instead of file as input, and commands are executed under shell. There is no reliable way to determine whether a command uses a file in asar archive, and even if we do, we can not be sure whether we can replace the path in command without side effects.

Adding Unpacked Files to asar Archives

As stated above, some Node APIs will unpack the file to the filesystem when called. Apart from the performance issues, various anti-virus scanners might be triggered by this behavior.

As a workaround, you can leave various files unpacked using the --unpack option. In the following example, shared libraries of native Node.js modules will not be packed:

$ asar pack app app.asar --unpack *.node

After running the command, you will notice that a folder named app.asar.unpacked was created together with the app.asar file. It contains the unpacked files and should be shipped together with the app.asar archive.


Technical Differences Between Electron and NW.js (formerly node-webkit)

Note: Electron was previously named Atom Shell.

Like NW.js, Electron provides a platform to write desktop applications with JavaScript and HTML and has Node integration to grant access to the low level system from web pages.

But there are also fundamental differences between the two projects that make Electron a completely separate product from NW.js:

1. Entry of Application

In NW.js the main entry point of an application is a web page or a JS script. You specify a html or js file in the package.json and it is opened in a browser window as the application's main window (in case of an html entrypoint) or the script is executed.

In Electron, the entry point is a JavaScript script. Instead of providing a URL directly, you manually create a browser window and load an HTML file using the API. You also need to listen to window events to decide when to quit the application.

Electron works more like the Node.js runtime. Electron's APIs are lower level so you can use it for browser testing in place of PhantomJS.

2. Build System

In order to avoid the complexity of building all of Chromium, Electron uses libchromiumcontent to access Chromium's Content API. libchromiumcontent is a single shared library that includes the Chromium Content module and all of its dependencies. Users don't need a powerful machine to build Electron.

3. Node Integration

In NW.js, the Node integration in web pages requires patching Chromium to work, while in Electron we chose a different way to integrate the libuv loop with each platform's message loop to avoid hacking Chromium. See the node_bindings code for how that was done.

4. Multi-context

If you are an experienced NW.js user, you should be familiar with the concept of Node context and web context. These concepts were invented because of how NW.js was implemented.

By using the multi-context feature of Node, Electron doesn't introduce a new JavaScript context in web pages.

Note: NW.js has optionally supported multi-context since 0.13.


autoUpdater

Enable apps to automatically update themselves.

Process: Main

See also: A detailed guide about how to implement updates in your application.

Platform Notices

Currently, only macOS and Windows are supported. There is no built-in support for auto-updater on Linux, so it is recommended to use the distribution's package manager to update your app.

In addition, there are some subtle differences on each platform:

macOS

On macOS, the autoUpdater module is built upon Squirrel.Mac, meaning you don't need any special setup to make it work. For server-side requirements, you can read Server Support. Note that App Transport Security (ATS) applies to all requests made as part of the update process. Apps that need to disable ATS can add the NSAllowsArbitraryLoads key to their app's plist.

Note: Your application must be signed for automatic updates on macOS. This is a requirement of Squirrel.Mac.

Windows

On Windows, you have to install your app into a user's machine before you can use the autoUpdater, so it is recommended that you use the electron-winstaller, electron-forge or the grunt-electron-installer package to generate a Windows installer.

When using electron-winstaller or electron-forge make sure you do not try to update your app the first time it runs (Also see this issue for more info). It's also recommended to use electron-squirrel-startup to get desktop shortcuts for your app.

The installer generated with Squirrel will create a shortcut icon with an Application User Model ID in the format of com.squirrel.PACKAGE_ID.YOUR_EXE_WITHOUT_DOT_EXE, examples are com.squirrel.slack.Slack and com.squirrel.code.Code. You have to use the same ID for your app with app.setAppUserModelId API, otherwise Windows will not be able to pin your app properly in task bar.

Unlike Squirrel.Mac, Windows can host updates on S3 or any other static file host. You can read the documents of Squirrel.Windows to get more details about how Squirrel.Windows works.

Events

The autoUpdater object emits the following events:

Event: 'error'

Returns:

  • error Error

Emitted when there is an error while updating.

Event: 'checking-for-update'

Emitted when checking if an update has started.

Event: 'update-available'

Emitted when there is an available update. The update is downloaded automatically.

Event: 'update-not-available'

Emitted when there is no available update.

Event: 'update-downloaded'

Returns:

  • event Event
  • releaseNotes String
  • releaseName String
  • releaseDate Date
  • updateURL String

Emitted when an update has been downloaded.

On Windows only releaseName is available.

Event: 'before-quit-for-update'

This event is emitted after a user calls quitAndInstall().

When this API is called, the before-quit event is not emitted before all windows are closed. As a result you should listen to this event if you wish to perform actions before the windows are closed while a process is quitting, as well as listening to before-quit.

Methods

The autoUpdater object has the following methods:

autoUpdater.setFeedURL(options)

  • options Object

    • url String
    • headers Object (optional) macOS - HTTP request headers.
    • serverType String (optional) macOS - Either json or default, see the Squirrel.Mac README for more information.

Sets the url and initialize the auto updater.

autoUpdater.getFeedURL()

Returns String - The current update feed URL.

autoUpdater.checkForUpdates()

Asks the server whether there is an update. You must call setFeedURL before using this API.

autoUpdater.quitAndInstall()

Restarts the app and installs the update after it has been downloaded. It should only be called after update-downloaded has been emitted.

Under the hood calling autoUpdater.quitAndInstall() will close all application windows first, and automatically call app.quit() after all windows have been closed.

Note: If the application is quit without calling this API after the update-downloaded event has been emitted, the application will still be replaced by the updated one on the next run.


Automated Testing with a Custom Driver

To write automated tests for your Electron app, you will need a way to "drive" your application. Spectron is a commonly-used solution which lets you emulate user actions via WebDriver. However, it's also possible to write your own custom driver using node's builtin IPC-over-STDIO. The benefit of a custom driver is that it tends to require less overhead than Spectron, and lets you expose custom methods to your test suite.

To create a custom driver, we'll use nodejs' child_process API. The test suite will spawn the Electron process, then establish a simple messaging protocol:

var childProcess = require('child_process')
var electronPath = require('electron')

// spawn the process
var env = { /* ... */ }
var stdio = ['inherit', 'inherit', 'inherit', 'ipc']
var appProcess = childProcess.spawn(electronPath, ['./app'], { stdio, env })

// listen for IPC messages from the app
appProcess.on('message', (msg) => {
  // ...
})

// send an IPC message to the app
appProcess.send({ my: 'message' })

From within the Electron app, you can listen for messages and send replies using the nodejs process API:

// listen for IPC messages from the test suite
process.on('message', (msg) => {
  // ...
})

// send an IPC message to the test suite
process.send({ my: 'message' })

We can now communicate from the test suite to the Electron app using the appProcess object.

For convenience, you may want to wrap appProcess in a driver object that provides more high-level functions. Here is an example of how you can do this:

class TestDriver {
  constructor ({ path, args, env }) {
    this.rpcCalls = []

    // start child process
    env.APP_TEST_DRIVER = 1 // let the app know it should listen for messages
    this.process = childProcess.spawn(path, args, { stdio: ['inherit', 'inherit', 'inherit', 'ipc'], env })

    // handle rpc responses
    this.process.on('message', (message) => {
      // pop the handler
      var rpcCall = this.rpcCalls[message.msgId]
      if (!rpcCall) return
      this.rpcCalls[message.msgId] = null
      // reject/resolve
      if (message.reject) rpcCall.reject(message.reject)
      else rpcCall.resolve(message.resolve)
    })

    // wait for ready
    this.isReady = this.rpc('isReady').catch((err) => {
      console.error('Application failed to start', err)
      this.stop()
      process.exit(1)
    })
  }

  // simple RPC call
  // to use: driver.rpc('method', 1, 2, 3).then(...)
  async rpc (cmd, ...args) {
    // send rpc request
    var msgId = this.rpcCalls.length
    this.process.send({ msgId, cmd, args })
    return new Promise((resolve, reject) => this.rpcCalls.push({ resolve, reject }))
  }

  stop () {
    this.process.kill()
  }
}

In the app, you'd need to write a simple handler for the RPC calls:

if (process.env.APP_TEST_DRIVER) {
  process.on('message', onMessage)
}

async function onMessage ({ msgId, cmd, args }) {
  var method = METHODS[cmd]
  if (!method) method = () => new Error('Invalid method: ' + cmd)
  try {
    var resolve = await method(...args)
    process.send({ msgId, resolve })
  } catch (err) {
    var reject = {
      message: err.message,
      stack: err.stack,
      name: err.name
    }
    process.send({ msgId, reject })
  }
}

const METHODS = {
  isReady () {
    // do any setup needed
    return true
  }
  // define your RPC-able methods here
}

Then, in your test suite, you can use your test-driver as follows:

var test = require('ava')
var electronPath = require('electron')

var app = new TestDriver({
  path: electronPath,
  args: ['./app'],
  env: {
    NODE_ENV: 'test'
  }
})
test.before(async t => {
  await app.isReady
})
test.after.always('cleanup', async t => {
  await app.stop()
})

BluetoothDevice Object

  • deviceName String
  • deviceId String

Boilerplates and CLIs

Electron development is un-opinionated - there is no "one true way" to develop, build, package, or release an Electron application. Additional features for Electron, both for build- and run-time, can usually be found on npm in individual packages, allowing developers to build both the app and build pipeline they need.

That level of modularity and extendability ensures that all developers working with Electron, both big and small in team-size, are never restricted in what they can or cannot do at any time during their development lifecycle. However, for many developers, one of the community-driven boilerplates or command line tools might make it dramatically easier to compile, package, and release an app.

Boilerplate vs CLI

A boilerplate is only a starting point - a canvas, so to speak - from which you build your application. They usually come in the form of a repository you can clone and customize to your heart's content.

A command line tool on the other hand continues to support you throughout the development and release. They are more helpful and supportive but enforce guidelines on how your code should be structured and built. Especially for beginners, using a command line tool is likely to be helpful.

electron-forge

A "complete tool for building modern Electron applications". Electron Forge unifies the existing (and well maintained) build tools for Electron development into a cohesive package so that anyone can jump right in to Electron development.

Forge comes with ready-to-use templates for popular frameworks like React, Vue, or Angular. It uses the same core modules used by the greater Electron community (like electron-packager) –  changes made by Electron maintainers (like Slack) benefit Forge's users, too.

You can find more information and documentation on electronforge.io.

electron-builder

A "complete solution to package and build a ready-for-distribution Electron app" that focuses on an integrated experience. electron-builder adds one single dependency focused on simplicity and manages all further requirements internally.

electron-builder replaces features and modules used by the Electron maintainers (such as the auto-updater) with custom ones. They are generally tighter integrated but will have less in common with popular Electron apps like Atom, Visual Studio Code, or Slack.

You can find more information and documentation in the repository.

electron-react-boilerplate

If you don't want any tools but only a solid boilerplate to build from, CT Lin's electron-react-boilerplate might be worth a look. It's quite popular in the community and uses electron-builder internally.

Other Tools and Boilerplates

The "Awesome Electron" list contains more tools and boilerplates to choose from. If you find the length of the list intimidating, don't forget that adding tools as you go along is a valid approach, too.


API Contract

Breaking changes will be documented here, and deprecation warnings added to JS code where possible, at least one major version before the change is made.

FIXME comments

The FIXME string is used in code comments to denote things that should be fixed for future releases. See https://github.com/electron/electron/search?q=fixme

Planned Breaking API Changes (4.0)

The following list includes the breaking API changes planned for Electron 4.0.

app.makeSingleInstance

// Deprecated
app.makeSingleInstance(function (argv, cwd) {

})
// Replace with
app.requestSingleInstanceLock()
app.on('second-instance', function (event, argv, cwd) {

})

app.releaseSingleInstance

// Deprecated
app.releaseSingleInstance()
// Replace with
app.releaseSingleInstanceLock()

Breaking API Changes (3.0)

The following list includes the breaking API changes in Electron 3.0.

app

// Deprecated
app.getAppMemoryInfo()
// Replace with
app.getAppMetrics()

// Deprecated
const metrics = app.getAppMetrics()
const {memory} = metrics[0]
memory.privateBytes  // Deprecated property
memory.sharedBytes  // Deprecated property

BrowserWindow

// Deprecated
let optionsA = {webPreferences: {blinkFeatures: ''}}
let windowA = new BrowserWindow(optionsA)
// Replace with
let optionsB = {webPreferences: {enableBlinkFeatures: ''}}
let windowB = new BrowserWindow(optionsB)

// Deprecated
window.on('app-command', (e, cmd) => {
  if (cmd === 'media-play_pause') {
    // do something
  }
})
// Replace with
window.on('app-command', (e, cmd) => {
  if (cmd === 'media-play-pause') {
    // do something
  }
})

clipboard

// Deprecated
clipboard.readRtf()
// Replace with
clipboard.readRTF()

// Deprecated
clipboard.writeRtf()
// Replace with
clipboard.writeRTF()

// Deprecated
clipboard.readHtml()
// Replace with
clipboard.readHTML()

// Deprecated
clipboard.writeHtml()
// Replace with
clipboard.writeHTML()

crashReporter

// Deprecated
crashReporter.start({
  companyName: 'Crashly',
  submitURL: 'https://crash.server.com',
  autoSubmit: true
})
// Replace with
crashReporter.start({
  companyName: 'Crashly',
  submitURL: 'https://crash.server.com',
  uploadToServer: true
})

nativeImage

// Deprecated
nativeImage.createFromBuffer(buffer, 1.0)
// Replace with
nativeImage.createFromBuffer(buffer, {
  scaleFactor: 1.0
})

process

// Deprecated
const info = process.getProcessMemoryInfo()
const privateBytes = info.privateBytes // deprecated property
const sharedBytes = info.sharedBytes // deprecated property

screen

// Deprecated
screen.getMenuBarHeight()
// Replace with
screen.getPrimaryDisplay().workArea

session

// Deprecated
ses.setCertificateVerifyProc(function (hostname, certificate, callback) {
  callback(true)
})
// Replace with
ses.setCertificateVerifyProc(function (request, callback) {
  callback(0)
})

Tray

// Deprecated
tray.setHighlightMode(true)
// Replace with
tray.setHighlightMode('on')

// Deprecated
tray.setHighlightMode(false)
// Replace with
tray.setHighlightMode('off')

webContents

// Deprecated
webContents.openDevTools({detach: true})
// Replace with
webContents.openDevTools({mode: 'detach'})

// Removed
webContents.setSize(options)
// There is no replacement for this API

webFrame

// Deprecated
webFrame.registerURLSchemeAsSecure('app')
// Replace with
protocol.registerStandardSchemes(['app'], {secure: true})

// Deprecated
webFrame.registerURLSchemeAsPrivileged('app', {secure: true})
// Replace with
protocol.registerStandardSchemes(['app'], {secure: true})

<webview>

// Removed
webview.setAttribute('disableguestresize', '')
// There is no replacement for this API

// Removed
webview.setAttribute('guestinstance', instanceId)
// There is no replacement for this API

// Keyboard listeners no longer work on webview tag
webview.onkeydown = () => { /* handler */ }
webview.onkeyup = () => { /* handler */ }

Node Headers URL

This is the URL specified as disturl in a .npmrc file or as the --dist-url command line flag when building native Node modules.

Deprecated: https://atom.io/download/atom-shell

Replace with: https://atom.io/download/electron

Breaking API Changes (2.0)

The following list includes the breaking API changes made in Electron 2.0.

BrowserWindow

// Deprecated
let optionsA = {titleBarStyle: 'hidden-inset'}
let windowA = new BrowserWindow(optionsA)
// Replace with
let optionsB = {titleBarStyle: 'hiddenInset'}
let windowB = new BrowserWindow(optionsB)
// Removed
menu.popup(browserWindow, 100, 200, 2)
// Replaced with
menu.popup(browserWindow, {x: 100, y: 200, positioningItem: 2})

nativeImage

// Removed
nativeImage.toPng()
// Replaced with
nativeImage.toPNG()

// Removed
nativeImage.toJpeg()
// Replaced with
nativeImage.toJPEG()

process

  • process.versions.electron and process.version.chrome will be made read-only properties for consistency with the other process.versions properties set by Node.

webContents

// Removed
webContents.setZoomLevelLimits(1, 2)
// Replaced with
webContents.setVisualZoomLevelLimits(1, 2)

webFrame

// Removed
webFrame.setZoomLevelLimits(1, 2)
// Replaced with
webFrame.setVisualZoomLevelLimits(1, 2)

<webview>

// Removed
webview.setZoomLevelLimits(1, 2)
// Replaced with
webview.setVisualZoomLevelLimits(1, 2)

Duplicate ARM Assets

Each Electron release includes two identical ARM builds with slightly different filenames, like electron-v1.7.3-linux-arm.zip and electron-v1.7.3-linux-armv7l.zip. The asset with the v7l prefix was added to clarify to users which ARM version it supports, and to disambiguate it from future armv6l and arm64 assets that may be produced.

The file without the prefix is still being published to avoid breaking any setups that may be consuming it. Starting at 2.0, the un-prefixed file will no longer be published.

For details, see 6986 and 7189.


Class: BrowserView

Create and control views.

Note: The BrowserView API is currently experimental and may change or be removed in future Electron releases.

Process: Main

A BrowserView can be used to embed additional web content into a BrowserWindow. It is like a child window, except that it is positioned relative to its owning window. It is meant to be an alternative to the webview tag.

Example

// In the main process.
const {BrowserView, BrowserWindow} = require('electron')

let win = new BrowserWindow({width: 800, height: 600})
win.on('closed', () => {
  win = null
})

let view = new BrowserView({
  webPreferences: {
    nodeIntegration: false
  }
})
win.setBrowserView(view)
view.setBounds({ x: 0, y: 0, width: 300, height: 300 })
view.webContents.loadURL('https://electronjs.org')

new BrowserView([options]) Experimental

  • options Object (optional)

BrowserView.getAllViews()

Returns BrowserView[] - An array of all opened BrowserViews.

BrowserView.fromWebContents(webContents)

Returns BrowserView | null - The BrowserView that owns the given webContents or null if the contents are not owned by a BrowserView.

BrowserView.fromId(id)

  • id Integer

Returns BrowserView - The view with the given id.

Instance Properties

Objects created with new BrowserView have the following properties:

view.webContents Experimental

A WebContents object owned by this view.

view.id Experimental

A Integer representing the unique ID of the view.

Instance Methods

Objects created with new BrowserView have the following instance methods:

view.destroy()

Force closing the view, the unload and beforeunload events won't be emitted for the web page. After you're done with a view, call this function in order to free memory and other resources as soon as possible.

view.isDestroyed()

Returns Boolean - Whether the view is destroyed.

view.setAutoResize(options) Experimental

  • options Object

    • width Boolean - If true, the view's width will grow and shrink together with the window. false by default.
    • height Boolean - If true, the view's height will grow and shrink together with the window. false by default.

view.setBounds(bounds) Experimental

Resizes and moves the view to the supplied bounds relative to the window.

view.setBackgroundColor(color) Experimental

  • color String - Color in #aarrggbb or #argb form. The alpha channel is optional.

BrowserWindow

Create and control browser windows.

Process: Main

// In the main process.
const {BrowserWindow} = require('electron')

// Or use `remote` from the renderer process.
// const {BrowserWindow} = require('electron').remote

let win = new BrowserWindow({width: 800, height: 600})
win.on('closed', () => {
  win = null
})

// Load a remote URL
win.loadURL('https://github.com')

// Or load a local HTML file
win.loadURL(`file://${__dirname}/app/index.html`)

Frameless window

To create a window without chrome, or a transparent window in arbitrary shape, you can use the Frameless Window API.

Showing window gracefully

When loading a page in the window directly, users may see the page load incrementally, which is not a good experience for a native app. To make the window display without visual flash, there are two solutions for different situations.

Using ready-to-show event

While loading the page, the ready-to-show event will be emitted when the renderer process has rendered the page for the first time if the window has not been shown yet. Showing the window after this event will have no visual flash:

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({show: false})
win.once('ready-to-show', () => {
  win.show()
})

This event is usually emitted after the did-finish-load event, but for pages with many remote resources, it may be emitted before the did-finish-load event.

Setting backgroundColor

For a complex app, the ready-to-show event could be emitted too late, making the app feel slow. In this case, it is recommended to show the window immediately, and use a backgroundColor close to your app's background:

const {BrowserWindow} = require('electron')

let win = new BrowserWindow({backgroundColor: '#2e2c29'})
win.loadURL('https://github.com')

Note that even for apps that use ready-to-show event, it is still recommended to set backgroundColor to make app feel more native.

Parent and child windows

By using parent option, you can create child windows:

const {BrowserWindow} = require('electron')

let top = new BrowserWindow()
let child = new BrowserWindow({parent: top})
child.show()
top.show()

The child window will always show on top of the top window.

A modal window is a child window that disables parent window, to create a modal window, you have to set both parent and modal options:

const {BrowserWindow} = require('electron')

let child = new BrowserWindow({parent: top, modal: true, show: false})
child.loadURL('https://github.com')
child.once('ready-to-show', () => {
  child.show()
})

Page visibility

The Page Visibility API works as follows:

  • On all platforms, the visibility state tracks whether the window is hidden/minimized or not.
  • Additionally, on macOS, the visibility state also tracks the window occlusion state. If the window is occluded (i.e. fully covered) by another window, the visibility state will be hidden. On other platforms, the visibility state will be hidden only when the window is minimized or explicitly hidden with win.hide().
  • If a BrowserWindow is created with show: false, the initial visibility state will be visible despite the window actually being hidden.
  • If backgroundThrottling is disabled, the visibility state will remain visible even if the window is minimized, occluded, or hidden.

It is recommended that you pause expensive operations when the visibility state is hidden in order to minimize power consumption.

Platform notices

  • On macOS modal windows will be displayed as sheets attached to the parent window.
  • On macOS the child windows will keep the relative position to parent window when parent window moves, while on Windows and Linux child windows will not move.
  • On Windows it is not supported to change parent window dynamically.
  • On Linux the type of modal windows will be changed to dialog.
  • On Linux many desktop environments do not support hiding a modal window.

Class: BrowserWindow

Create and control browser windows.

Process: Main

BrowserWindow is an EventEmitter.

It creates a new BrowserWindow with native properties as set by the options.

new BrowserWindow([options])

  • options Object (optional)

    • width Integer (optional) - Window's width in pixels. Default is 800.
    • height Integer (optional) - Window's height in pixels. Default is 600.
    • x Integer (optional) (required if y is used) - Window's left offset from screen. Default is to center the window.
    • y Integer (optional) (required if x is used) - Window's top offset from screen. Default is to center the window.
    • useContentSize Boolean (optional) - The width and height would be used as web page's size, which means the actual window's size will include window frame's size and be slightly larger. Default is false.
    • center Boolean (optional) - Show window in the center of the screen.
    • minWidth Integer (optional) - Window's minimum width. Default is 0.
    • minHeight Integer (optional) - Window's minimum height. Default is 0.
    • maxWidth Integer (optional) - Window's maximum width. Default is no limit.
    • maxHeight Integer (optional) - Window's maximum height. Default is no limit.
    • resizable Boolean (optional) - Whether window is resizable. Default is true.
    • movable Boolean (optional) - Whether window is movable. This is not implemented on Linux. Default is true.
    • minimizable Boolean (optional) - Whether window is minimizable. This is not implemented on Linux. Default is true.
    • maximizable Boolean (optional) - Whether window is maximizable. This is not implemented on Linux. Default is true.
    • closable Boolean (optional) - Whether window is closable. This is not implemented on Linux. Default is true.
    • focusable Boolean (optional) - Whether the window can be focused. Default is true. On Windows setting focusable: false also implies setting skipTaskbar: true. On Linux setting focusable: false makes the window stop interacting with wm, so the window will always stay on top in all workspaces.
    • alwaysOnTop Boolean (optional) - Whether the window should always stay on top of other windows. Default is false.
    • fullscreen Boolean (optional) - Whether the window should show in fullscreen. When explicitly set to false the fullscreen button will be hidden or disabled on macOS. Default is false.
    • fullscreenable Boolean (optional) - Whether the window can be put into fullscreen mode. On macOS, also whether the maximize/zoom button should toggle full screen mode or maximize window. Default is true.
    • simpleFullscreen Boolean (optional) - Use pre-Lion fullscreen on macOS. Default is false.
    • skipTaskbar Boolean (optional) - Whether to show the window in taskbar. Default is false.
    • kiosk Boolean (optional) - The kiosk mode. Default is false.
    • title String (optional) - Default window title. Default is "Electron".
    • icon (NativeImage | String) (optional) - The window icon. On Windows it is recommended to use ICO icons to get best visual effects, you can also leave it undefined so the executable's icon will be used.
    • show Boolean (optional) - Whether window should be shown when created. Default is true.
    • frame Boolean (optional) - Specify false to create a Frameless Window. Default is true.
    • parent BrowserWindow (optional) - Specify parent window. Default is null.
    • modal Boolean (optional) - Whether this is a modal window. This only works when the window is a child window. Default is false.
    • acceptFirstMouse Boolean (optional) - Whether the web view accepts a single mouse-down event that simultaneously activates the window. Default is false.
    • disableAutoHideCursor Boolean (optional) - Whether to hide cursor when typing. Default is false.
    • autoHideMenuBar Boolean (optional) - Auto hide the menu bar unless the Alt key is pressed. Default is false.
    • enableLargerThanScreen Boolean (optional) - Enable the window to be resized larger than screen. Default is false.
    • backgroundColor String (optional) - Window's background color as a hexadecimal value, like #66CD00 or #FFF or #80FFFFFF (alpha is supported). Default is #FFF (white). If transparent is set to true, only values with transparent (#00-------) or opaque (#FF-----) alpha values are respected.
    • hasShadow Boolean (optional) - Whether window should have a shadow. This is only implemented on macOS. Default is true.
    • opacity Number (optional) - Set the initial opacity of the window, between 0.0 (fully transparent) and 1.0 (fully opaque). This is only implemented on Windows and macOS.
    • darkTheme Boolean (optional) - Forces using dark theme for the window, only works on some GTK+3 desktop environments. Default is false.
    • transparent Boolean (optional) - Makes the window transparent. Default is false.
    • type String (optional) - The type of window, default is normal window. See more about this below.
    • titleBarStyle String (optional) - The style of window title bar. Default is default. Possible values are:

      • default - Results in the standard gray opaque Mac title bar.
      • hidden - Results in a hidden title bar and a full size content window, yet the title bar still has the standard window controls ("traffic lights") in the top left.
      • hiddenInset - Results in a hidden title bar with an alternative look where the traffic light buttons are slightly more inset from the window edge.
      • customButtonsOnHover Boolean (optional) - Draw custom close, minimize, and full screen buttons on macOS frameless windows. These buttons will not display unless hovered over in the top left of the window. These custom buttons prevent issues with mouse events that occur with the standard window toolbar buttons. Note: This option is currently experimental.
    • fullscreenWindowTitle Boolean (optional) - Shows the title in the title bar in full screen mode on macOS for all titleBarStyle options. Default is false.
    • thickFrame Boolean (optional) - Use WS_THICKFRAME style for frameless windows on Windows, which adds standard window frame. Setting it to false will remove window shadow and window animations. Default is true.
    • vibrancy String (optional) - Add a type of vibrancy effect to the window, only on macOS. Can be appearance-based, light, dark, titlebar, selection, menu, popover, sidebar, medium-light or ultra-dark. Please note that using frame: false in combination with a vibrancy value requires that you use a non-default titleBarStyle as well.
    • zoomToPageWidth Boolean (optional) - Controls the behavior on macOS when option-clicking the green stoplight button on the toolbar or by clicking the Window > Zoom menu item. If true, the window will grow to the preferred width of the web page when zoomed, false will cause it to zoom to the width of the screen. This will also affect the behavior when calling maximize() directly. Default is false.
    • tabbingIdentifier String (optional) - Tab group name, allows opening the window as a native tab on macOS 10.12+. Windows with the same tabbing identifier will be grouped together. This also adds a native new tab button to your window's tab bar and allows your app and window to receive the new-window-for-tab event.
    • webPreferences Object (optional) - Settings of web page's features.

      • devTools Boolean (optional) - Whether to enable DevTools. If it is set to false, can not use BrowserWindow.webContents.openDevTools() to open DevTools. Default is true.
      • nodeIntegration Boolean (optional) - Whether node integration is enabled. Default is true.
      • nodeIntegrationInWorker Boolean (optional) - Whether node integration is enabled in web workers. Default is false. More about this can be found in Multithreading.
      • preload String (optional) - Specifies a script that will be loaded before other scripts run in the page. This script will always have access to node APIs no matter whether node integration is turned on or off. The value should be the absolute file path to the script. When node integration is turned off, the preload script can reintroduce Node global symbols back to the global scope. See example here.
      • sandbox Boolean (optional) - If set, this will sandbox the renderer associated with the window, making it compatible with the Chromium OS-level sandbox and disabling the Node.js engine. This is not the same as the nodeIntegration option and the APIs available to the preload script are more limited. Read more about the option here. Note: This option is currently experimental and may change or be removed in future Electron releases.
      • session Session (optional) - Sets the session used by the page. Instead of passing the Session object directly, you can also choose to use the partition option instead, which accepts a partition string. When both session and partition are provided, session will be preferred. Default is the default session.
      • partition String (optional) - Sets the session used by the page according to the session's partition string. If partition starts with persist:, the page will use a persistent session available to all pages in the app with the same partition. If there is no persist: prefix, the page will use an in-memory session. By assigning the same partition, multiple pages can share the same session. Default is the default session.
      • affinity String (optional) - When specified, web pages with the same affinity will run in the same renderer process. Note that due to reusing the renderer process, certain webPreferences options will also be shared between the web pages even when you specified different values for them, including but not limited to preload, sandbox and nodeIntegration. So it is suggested to use exact same webPreferences for web pages with the same affinity. This property is experimental
      • zoomFactor Number (optional) - The default zoom factor of the page, 3.0 represents 300%. Default is 1.0.
      • javascript Boolean (optional) - Enables JavaScript support. Default is true.
      • webSecurity Boolean (optional) - When false, it will disable the same-origin policy (usually using testing websites by people), and set allowRunningInsecureContent to true if this options has not been set by user. Default is true.
      • allowRunningInsecureContent Boolean (optional) - Allow an https page to run JavaScript, CSS or plugins from http URLs. Default is false.
      • images Boolean (optional) - Enables image support. Default is true.
      • textAreasAreResizable Boolean (optional) - Make TextArea elements resizable. Default is true.
      • webgl Boolean (optional) - Enables WebGL support. Default is true.
      • webaudio Boolean (optional) - Enables WebAudio support. Default is true.
      • plugins Boolean (optional) - Whether plugins should be enabled. Default is false.
      • experimentalFeatures Boolean (optional) - Enables Chromium's experimental features. Default is false.
      • experimentalCanvasFeatures Boolean (optional) - Enables Chromium's experimental canvas features. Default is false.
      • scrollBounce Boolean (optional) - Enables scroll bounce (rubber banding) effect on macOS. Default is false.
      • enableBlinkFeatures String (optional) - A list of feature strings separated by ,, like CSSVariables,KeyboardEventKey to enable. The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file.
      • disableBlinkFeatures String (optional) - A list of feature strings separated by ,, like CSSVariables,KeyboardEventKey to disable. The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file.
      • defaultFontFamily Object (optional) - Sets the default font for the font-family.

        • standard String (optional) - Defaults to Times New Roman.
        • serif String (optional) - Defaults to Times New Roman.
        • sansSerif String (optional) - Defaults to Arial.
        • monospace String (optional) - Defaults to Courier New.
        • cursive String (optional) - Defaults to Script.
        • fantasy String (optional) - Defaults to Impact.
      • defaultFontSize Integer (optional) - Defaults to 16.
      • defaultMonospaceFontSize Integer (optional) - Defaults to 13.
      • minimumFontSize Integer (optional) - Defaults to 0.
      • defaultEncoding String (optional) - Defaults to ISO-8859-1.
      • backgroundThrottling Boolean (optional) - Whether to throttle animations and timers when the page becomes background. This also affects the Page Visibility API. Defaults to true.
      • offscreen Boolean (optional) - Whether to enable offscreen rendering for the browser window. Defaults to false. See the offscreen rendering tutorial for more details.
      • contextIsolation Boolean (optional) - Whether to run Electron APIs and the specified preload script in a separate JavaScript context. Defaults to false. The context that the preload script runs in will still have full access to the document and window globals but it will use its own set of JavaScript builtins (Array, Object, JSON, etc.) and will be isolated from any changes made to the global environment by the loaded page. The Electron API will only be available in the preload script and not the loaded page. This option should be used when loading potentially untrusted remote content to ensure the loaded content cannot tamper with the preload script and any Electron APIs being used. This option uses the same technique used by Chrome Content Scripts. You can access this context in the dev tools by selecting the 'Electron Isolated Context' entry in the combo box at the top of the Console tab. Note: This option is currently experimental and may change or be removed in future Electron releases.
      • nativeWindowOpen Boolean (optional) - Whether to use native window.open(). If set to true, the webPreferences of child window will always be the same with parent window, regardless of the parameters passed to window.open(). Defaults to false. Note: This option is currently experimental.
      • webviewTag Boolean (optional) - Whether to enable the <webview> tag. Defaults to the value of the nodeIntegration option. Note: The preload script configured for the <webview> will have node integration enabled when it is executed so you should ensure remote/untrusted content is not able to create a <webview> tag with a possibly malicious preload script. You can use the will-attach-webview event on webContents to strip away the preload script and to validate or alter the <webview>'s initial settings.
      • additionalArguments String - A list of strings that will be appended to process.argv in the renderer process of this app. Useful for passing small bits of data down to renderer process preload scripts.
      • safeDialogs Boolean (optional) - Whether to enable browser style consecutive dialog protection. Default is false.
      • safeDialogsMessage String (optional) - The message to display when consecutive dialog protection is triggered. If not defined the default message would be used, note that currently the default message is in English and not localized.
      • navigateOnDragDrop Boolean (optional) - Whether dragging and dropping a file or link onto the page causes a navigation. Default is false.

When setting minimum or maximum window size with minWidth/maxWidth/ minHeight/maxHeight, it only constrains the users. It won't prevent you from passing a size that does not follow size constraints to setBounds/setSize or to the constructor of BrowserWindow.

The possible values and behaviors of the type option are platform dependent. Possible values are:

  • On Linux, possible types are desktop, dock, toolbar, splash, notification.
  • On macOS, possible types are desktop, textured.

    • The textured type adds metal gradient appearance (NSTexturedBackgroundWindowMask).
    • The desktop type places the window at the desktop background window level (kCGDesktopWindowLevel - 1). Note that desktop window will not receive focus, keyboard or mouse events, but you can use globalShortcut to receive input sparingly.
  • On Windows, possible type is toolbar.

Instance Events

Objects created with new BrowserWindow emit the following events:

Note: Some events are only available on specific operating systems and are labeled as such.

Event: 'page-title-updated'

Returns:

  • event Event
  • title String

Emitted when the document changed its title, calling event.preventDefault() will prevent the native window's title from changing.

Event: 'close'

Returns:

  • event Event

Emitted when the window is going to be closed. It's emitted before the beforeunload and unload event of the DOM. Calling event.preventDefault() will cancel the close.

Usually you would want to use the beforeunload handler to decide whether the window should be closed, which will also be called when the window is reloaded. In Electron, returning any value other than undefined would cancel the close. For example:

window.onbeforeunload = (e) => {
  console.log('I do not want to be closed')

  // Unlike usual browsers that a message box will be prompted to users, returning
  // a non-void value will silently cancel the close.
  // It is recommended to use the dialog API to let the user confirm closing the
  // application.
  e.returnValue = false // equivalent to `return false` but not recommended
}

Note: There is a subtle difference between the behaviors of window.onbeforeunload = handler and window.addEventListener('beforeunload', handler). It is recommended to always set the event.returnValue explicitly, instead of only returning a value, as the former works more consistently within Electron.

Event: 'closed'

Emitted when the window is closed. After you have received this event you should remove the reference to the window and avoid using it any more.

Event: 'session-end' Windows

Emitted when window session is going to end due to force shutdown or machine restart or session log off.

Event: 'unresponsive'

Emitted when the web page becomes unresponsive.

Event: 'responsive'

Emitted when the unresponsive web page becomes responsive again.

Event: 'blur'

Emitted when the window loses focus.

Event: 'focus'

Emitted when the window gains focus.

Event: 'show'

Emitted when the window is shown.

Event: 'hide'

Emitted when the window is hidden.

Event: 'ready-to-show'

Emitted when the web page has been rendered (while not being shown) and window can be displayed without a visual flash.

Event: 'maximize'

Emitted when window is maximized.

Event: 'unmaximize'

Emitted when the window exits from a maximized state.

Event: 'minimize'

Emitted when the window is minimized.

Event: 'restore'

Emitted when the window is restored from a minimized state.

Event: 'resize'

Emitted when the window is being resized.

Event: 'move'

Emitted when the window is being moved to a new position.

Note: On macOS this event is an alias of moved.

Event: 'moved' macOS

Emitted once when the window is moved to a new position.

Event: 'enter-full-screen'

Emitted when the window enters a full-screen state.

Event: 'leave-full-screen'

Emitted when the window leaves a full-screen state.

Event: 'enter-html-full-screen'

Emitted when the window enters a full-screen state triggered by HTML API.

Event: 'leave-html-full-screen'

Emitted when the window leaves a full-screen state triggered by HTML API.

Event: 'app-command' Windows

Returns:

  • event Event
  • command String

Emitted when an App Command is invoked. These are typically related to keyboard media keys or browser commands, as well as the "Back" button built into some mice on Windows.

Commands are lowercased, underscores are replaced with hyphens, and the APPCOMMAND_ prefix is stripped off. e.g. APPCOMMAND_BROWSER_BACKWARD is emitted as browser-backward.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()
win.on('app-command', (e, cmd) => {
  // Navigate the window back when the user hits their mouse back button
  if (cmd === 'browser-backward' && win.webContents.canGoBack()) {
    win.webContents.goBack()
  }
})

Event: 'scroll-touch-begin' macOS

Emitted when scroll wheel event phase has begun.

Event: 'scroll-touch-end' macOS

Emitted when scroll wheel event phase has ended.

Event: 'scroll-touch-edge' macOS

Emitted when scroll wheel event phase filed upon reaching the edge of element.

Event: 'swipe' macOS

Returns:

  • event Event
  • direction String

Emitted on 3-finger swipe. Possible directions are up, right, down, left.

Event: 'sheet-begin' macOS

Emitted when the window opens a sheet.

Event: 'sheet-end' macOS

Emitted when the window has closed a sheet.

Event: 'new-window-for-tab' macOS

Emitted when the native new tab button is clicked.

Static Methods

The BrowserWindow class has the following static methods:

BrowserWindow.getAllWindows()

Returns BrowserWindow[] - An array of all opened browser windows.

BrowserWindow.getFocusedWindow()

Returns BrowserWindow | null - The window that is focused in this application, otherwise returns null.

BrowserWindow.fromWebContents(webContents)

Returns BrowserWindow - The window that owns the given webContents.

BrowserWindow.fromBrowserView(browserView)

Returns BrowserWindow | null - The window that owns the given browserView. If the given view is not attached to any window, returns null.

BrowserWindow.fromId(id)

  • id Integer

Returns BrowserWindow - The window with the given id.

BrowserWindow.addExtension(path)

  • path String

Adds Chrome extension located at path, and returns extension's name.

The method will also not return if the extension's manifest is missing or incomplete.

Note: This API cannot be called before the ready event of the app module is emitted.

BrowserWindow.removeExtension(name)

  • name String

Remove a Chrome extension by name.

Note: This API cannot be called before the ready event of the app module is emitted.

BrowserWindow.getExtensions()

Returns Object - The keys are the extension names and each value is an Object containing name and version properties.

Note: This API cannot be called before the ready event of the app module is emitted.

BrowserWindow.addDevToolsExtension(path)

  • path String

Adds DevTools extension located at path, and returns extension's name.

The extension will be remembered so you only need to call this API once, this API is not for programming use. If you try to add an extension that has already been loaded, this method will not return and instead log a warning to the console.

The method will also not return if the extension's manifest is missing or incomplete.

Note: This API cannot be called before the ready event of the app module is emitted.

BrowserWindow.removeDevToolsExtension(name)

  • name String

Remove a DevTools extension by name.

Note: This API cannot be called before the ready event of the app module is emitted.

BrowserWindow.getDevToolsExtensions()

Returns Object - The keys are the extension names and each value is an Object containing name and version properties.

To check if a DevTools extension is installed you can run the following:

const {BrowserWindow} = require('electron')

let installed = BrowserWindow.getDevToolsExtensions().hasOwnProperty('devtron')
console.log(installed)

Note: This API cannot be called before the ready event of the app module is emitted.

Instance Properties

Objects created with new BrowserWindow have the following properties:

const {BrowserWindow} = require('electron')
// In this example `win` is our instance
let win = new BrowserWindow({width: 800, height: 600})
win.loadURL('https://github.com')

win.webContents

A WebContents object this window owns. All web page related events and operations will be done via it.

See the webContents documentation for its methods and events.

win.id

A Integer representing the unique ID of the window.

Instance Methods

Objects created with new BrowserWindow have the following instance methods:

Note: Some methods are only available on specific operating systems and are labeled as such.

win.destroy()

Force closing the window, the unload and beforeunload event won't be emitted for the web page, and close event will also not be emitted for this window, but it guarantees the closed event will be emitted.

win.close()

Try to close the window. This has the same effect as a user manually clicking the close button of the window. The web page may cancel the close though. See the close event.

win.focus()

Focuses on the window.

win.blur()

Removes focus from the window.

win.isFocused()

Returns Boolean - Whether the window is focused.

win.isDestroyed()

Returns Boolean - Whether the window is destroyed.

win.show()

Shows and gives focus to the window.

win.showInactive()

Shows the window but doesn't focus on it.

win.hide()

Hides the window.

win.isVisible()

Returns Boolean - Whether the window is visible to the user.

win.isModal()

Returns Boolean - Whether current window is a modal window.

win.maximize()

Maximizes the window. This will also show (but not focus) the window if it isn't being displayed already.

win.unmaximize()

Unmaximizes the window.

win.isMaximized()

Returns Boolean - Whether the window is maximized.

win.minimize()

Minimizes the window. On some platforms the minimized window will be shown in the Dock.

win.restore()

Restores the window from minimized state to its previous state.

win.isMinimized()

Returns Boolean - Whether the window is minimized.

win.setFullScreen(flag)

  • flag Boolean

Sets whether the window should be in fullscreen mode.

win.isFullScreen()

Returns Boolean - Whether the window is in fullscreen mode.

win.setSimpleFullScreen(flag) macOS

  • flag Boolean

Enters or leaves simple fullscreen mode.

Simple fullscreen mode emulates the native fullscreen behavior found in versions of Mac OS X prior to Lion (10.7).

win.isSimpleFullScreen() macOS

Returns Boolean - Whether the window is in simple (pre-Lion) fullscreen mode.

win.setAspectRatio(aspectRatio[, extraSize]) macOS

  • aspectRatio Float - The aspect ratio to maintain for some portion of the content view.
  • extraSize Size - The extra size not to be included while maintaining the aspect ratio.

This will make a window maintain an aspect ratio. The extra size allows a developer to have space, specified in pixels, not included within the aspect ratio calculations. This API already takes into account the difference between a window's size and its content size.

Consider a normal window with an HD video player and associated controls. Perhaps there are 15 pixels of controls on the left edge, 25 pixels of controls on the right edge and 50 pixels of controls below the player. In order to maintain a 16:9 aspect ratio (standard aspect ratio for HD @1920x1080) within the player itself we would call this function with arguments of 16/9 and [ 40, 50 ]. The second argument doesn't care where the extra width and height are within the content view--only that they exist. Sum any extra width and height areas you have within the overall content view.

Calling this function with a value of 0 will remove any previously set aspect ratios.

win.previewFile(path[, displayName]) macOS

  • path String - The absolute path to the file to preview with QuickLook. This is important as Quick Look uses the file name and file extension on the path to determine the content type of the file to open.
  • displayName String (optional) - The name of the file to display on the Quick Look modal view. This is purely visual and does not affect the content type of the file. Defaults to path.

Uses Quick Look to preview a file at a given path.

win.closeFilePreview() macOS

Closes the currently open Quick Look panel.

win.setBounds(bounds[, animate])

  • bounds Rectangle
  • animate Boolean (optional) macOS

Resizes and moves the window to the supplied bounds

win.setContentBounds(bounds[, animate])

  • bounds Rectangle
  • animate Boolean (optional) macOS

Resizes and moves the window's client area (e.g. the web page) to the supplied bounds.

win.setEnabled(enable)

  • enable Boolean

Disable or enable the window.

win.setSize(width, height[, animate])

  • width Integer
  • height Integer
  • animate Boolean (optional) macOS

Resizes the window to width and height. If width or height are below any set minimum size constraints the window will snap to its minimum size.

win.getSize()

Returns Integer[] - Contains the window's width and height.

win.setContentSize(width, height[, animate])

  • width Integer
  • height Integer
  • animate Boolean (optional) macOS

Resizes the window's client area (e.g. the web page) to width and height.

win.getContentSize()

Returns Integer[] - Contains the window's client area's width and height.

win.setMinimumSize(width, height)

  • width Integer
  • height Integer

Sets the minimum size of window to width and height.

win.getMinimumSize()

Returns Integer[] - Contains the window's minimum width and height.

win.setMaximumSize(width, height)

  • width Integer
  • height Integer

Sets the maximum size of window to width and height.

win.getMaximumSize()

Returns Integer[] - Contains the window's maximum width and height.

win.setResizable(resizable)

  • resizable Boolean

Sets whether the window can be manually resized by user.

win.isResizable()

Returns Boolean - Whether the window can be manually resized by user.

win.setMovable(movable) macOS Windows

  • movable Boolean

Sets whether the window can be moved by user. On Linux does nothing.

win.isMovable() macOS Windows

Returns Boolean - Whether the window can be moved by user.

On Linux always returns true.

win.setMinimizable(minimizable) macOS Windows

  • minimizable Boolean

Sets whether the window can be manually minimized by user. On Linux does nothing.

win.isMinimizable() macOS Windows

Returns Boolean - Whether the window can be manually minimized by user

On Linux always returns true.

win.setMaximizable(maximizable) macOS Windows

  • maximizable Boolean

Sets whether the window can be manually maximized by user. On Linux does nothing.

win.isMaximizable() macOS Windows

Returns Boolean - Whether the window can be manually maximized by user.

On Linux always returns true.

win.setFullScreenable(fullscreenable)

  • fullscreenable Boolean

Sets whether the maximize/zoom window button toggles fullscreen mode or maximizes the window.

win.isFullScreenable()

Returns Boolean - Whether the maximize/zoom window button toggles fullscreen mode or maximizes the window.

win.setClosable(closable) macOS Windows

  • closable Boolean

Sets whether the window can be manually closed by user. On Linux does nothing.

win.isClosable() macOS Windows

Returns Boolean - Whether the window can be manually closed by user.

On Linux always returns true.

win.setAlwaysOnTop(flag[, level][, relativeLevel])

  • flag Boolean
  • level String (optional) macOS - Values include normal, floating, torn-off-menu, modal-panel, main-menu, status, pop-up-menu, screen-saver, and dock (Deprecated). The default is floating. See the macOS docs for more details.
  • relativeLevel Integer (optional) macOS - The number of layers higher to set this window relative to the given level. The default is 0. Note that Apple discourages setting levels higher than 1 above screen-saver.

Sets whether the window should show always on top of other windows. After setting this, the window is still a normal window, not a toolbox window which can not be focused on.

win.isAlwaysOnTop()

Returns Boolean - Whether the window is always on top of other windows.

win.moveTop() macOS Windows

Moves window to top(z-order) regardless of focus

win.center()

Moves window to the center of the screen.

win.setPosition(x, y[, animate])

  • x Integer
  • y Integer
  • animate Boolean (optional) macOS

Moves window to x and y.

win.getPosition()

Returns Integer[] - Contains the window's current position.

win.setTitle(title)

  • title String

Changes the title of native window to title.

win.getTitle()

Returns String - The title of the native window.

Note: The title of web page can be different from the title of the native window.

win.setSheetOffset(offsetY[, offsetX]) macOS

  • offsetY Float
  • offsetX Float (optional)

Changes the attachment point for sheets on macOS. By default, sheets are attached just below the window frame, but you may want to display them beneath a HTML-rendered toolbar. For example:

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()

let toolbarRect = document.getElementById('toolbar').getBoundingClientRect()
win.setSheetOffset(toolbarRect.height)

win.flashFrame(flag)

  • flag Boolean

Starts or stops flashing the window to attract user's attention.

win.setSkipTaskbar(skip)

  • skip Boolean

Makes the window not show in the taskbar.

win.setKiosk(flag)

  • flag Boolean

Enters or leaves the kiosk mode.

win.isKiosk()

Returns Boolean - Whether the window is in kiosk mode.

win.getNativeWindowHandle()

Returns Buffer - The platform-specific handle of the window.

The native type of the handle is HWND on Windows, NSView* on macOS, and Window (unsigned long) on Linux.

win.hookWindowMessage(message, callback) Windows

  • message Integer
  • callback Function

Hooks a windows message. The callback is called when the message is received in the WndProc.

win.isWindowMessageHooked(message) Windows

  • message Integer

Returns Boolean - true or false depending on whether the message is hooked.

win.unhookWindowMessage(message) Windows

  • message Integer

Unhook the window message.

win.unhookAllWindowMessages() Windows

Unhooks all of the window messages.

win.setRepresentedFilename(filename) macOS

  • filename String

Sets the pathname of the file the window represents, and the icon of the file will show in window's title bar.

win.getRepresentedFilename() macOS

Returns String - The pathname of the file the window represents.

win.setDocumentEdited(edited) macOS

  • edited Boolean

Specifies whether the window’s document has been edited, and the icon in title bar will become gray when set to true.

win.isDocumentEdited() macOS

Returns Boolean - Whether the window's document has been edited.

win.capturePage([rect, ]callback)

Same as webContents.capturePage([rect, ]callback).

win.loadURL(url[, options])

  • url String
  • options Object (optional)

    • httpReferrer (String | Referrer) (optional) - An HTTP Referrer url.
    • userAgent String (optional) - A user agent originating the request.
    • extraHeaders String (optional) - Extra headers separated by "\n"
    • postData (UploadRawData[] | UploadFile[] | UploadBlob[]) (optional)
    • baseURLForDataURL String (optional) - Base url (with trailing path separator) for files to be loaded by the data url. This is needed only if the specified url is a data url and needs to load other files.

Same as webContents.loadURL(url[, options]).

The url can be a remote address (e.g. http://) or a path to a local HTML file using the file:// protocol.

To ensure that file URLs are properly formatted, it is recommended to use Node's url.format method:

let url = require('url').format({
  protocol: 'file',
  slashes: true,
  pathname: require('path').join(__dirname, 'index.html')
})

win.loadURL(url)

You can load a URL using a POST request with URL-encoded data by doing the following:

win.loadURL('http://localhost:8000/post', {
  postData: [{
    type: 'rawData',
    bytes: Buffer.from('hello=world')
  }],
  extraHeaders: 'Content-Type: application/x-www-form-urlencoded'
})

win.loadFile(filePath)

  • filePath String

Same as webContents.loadFile, filePath should be a path to an HTML file relative to the root of your application. See the webContents docs for more information.

win.reload()

Same as webContents.reload.

win.setMenu(menu) Linux Windows

  • menu Menu | null

Sets the menu as the window's menu bar, setting it to null will remove the menu bar.

win.setProgressBar(progress[, options])

  • progress Double
  • options Object (optional)

    • mode String Windows - Mode for the progress bar. Can be none, normal, indeterminate, error or paused.

Sets progress value in progress bar. Valid range is [0, 1.0].

Remove progress bar when progress < 0; Change to indeterminate mode when progress > 1.

On Linux platform, only supports Unity desktop environment, you need to specify the *.desktop file name to desktopName field in package.json. By default, it will assume app.getName().desktop.

On Windows, a mode can be passed. Accepted values are none, normal, indeterminate, error, and paused. If you call setProgressBar without a mode set (but with a value within the valid range), normal will be assumed.

win.setOverlayIcon(overlay, description) Windows

  • overlay NativeImage | null - the icon to display on the bottom right corner of the taskbar icon. If this parameter is null, the overlay is cleared
  • description String - a description that will be provided to Accessibility screen readers

Sets a 16 x 16 pixel overlay onto the current taskbar icon, usually used to convey some sort of application status or to passively notify the user.

win.setHasShadow(hasShadow) macOS

  • hasShadow Boolean

Sets whether the window should have a shadow. On Windows and Linux does nothing.

win.hasShadow() macOS

Returns Boolean - Whether the window has a shadow.

On Windows and Linux always returns true.

win.setOpacity(opacity) Windows macOS

  • opacity Number - between 0.0 (fully transparent) and 1.0 (fully opaque)

Sets the opacity of the window. On Linux does nothing.

win.getOpacity() Windows macOS

Returns Number - between 0.0 (fully transparent) and 1.0 (fully opaque)

win.setShape(rects) Windows Linux Experimental

  • rects Rectangle[] - Sets a shape on the window. Passing an empty list reverts the window to being rectangular.

Setting a window shape determines the area within the window where the system permits drawing and user interaction. Outside of the given region, no pixels will be drawn and no mouse events will be registered. Mouse events outside of the region will not be received by that window, but will fall through to whatever is behind the window.

win.setThumbarButtons(buttons) Windows

Returns Boolean - Whether the buttons were added successfully

Add a thumbnail toolbar with a specified set of buttons to the thumbnail image of a window in a taskbar button layout. Returns a Boolean object indicates whether the thumbnail has been added successfully.

The number of buttons in thumbnail toolbar should be no greater than 7 due to the limited room. Once you setup the thumbnail toolbar, the toolbar cannot be removed due to the platform's limitation. But you can call the API with an empty array to clean the buttons.

The buttons is an array of Button objects:

  • Button Object

    • icon NativeImage - The icon showing in thumbnail toolbar.
    • click Function
    • tooltip String (optional) - The text of the button's tooltip.
    • flags String - Control specific states and behaviors of the button. By default, it is ['enabled'].

The flags is an array that can include following Strings:

  • enabled - The button is active and available to the user.
  • disabled - The button is disabled. It is present, but has a visual state indicating it will not respond to user action.
  • dismissonclick - When the button is clicked, the thumbnail window closes immediately.
  • nobackground - Do not draw a button border, use only the image.
  • hidden - The button is not shown to the user.
  • noninteractive - The button is enabled but not interactive; no pressed button state is drawn. This value is intended for instances where the button is used in a notification.

win.setThumbnailClip(region) Windows

Sets the region of the window to show as the thumbnail image displayed when hovering over the window in the taskbar. You can reset the thumbnail to be the entire window by specifying an empty region: {x: 0, y: 0, width: 0, height: 0}.

win.setThumbnailToolTip(toolTip) Windows

  • toolTip String

Sets the toolTip that is displayed when hovering over the window thumbnail in the taskbar.

win.setAppDetails(options) Windows

  • options Object

    • appId String (optional) - Window's App User Model ID. It has to be set, otherwise the other options will have no effect.
    • appIconPath String (optional) - Window's Relaunch Icon.
    • appIconIndex Integer (optional) - Index of the icon in appIconPath. Ignored when appIconPath is not set. Default is 0.
    • relaunchCommand String (optional) - Window's Relaunch Command.
    • relaunchDisplayName String (optional) - Window's Relaunch Display Name.

Sets the properties for the window's taskbar button.

Note: relaunchCommand and relaunchDisplayName must always be set together. If one of those properties is not set, then neither will be used.

win.showDefinitionForSelection() macOS

Same as webContents.showDefinitionForSelection().

win.setIcon(icon) Windows Linux

Changes window icon.

win.setAutoHideMenuBar(hide)

  • hide Boolean

Sets whether the window menu bar should hide itself automatically. Once set the menu bar will only show when users press the single Alt key.

If the menu bar is already visible, calling setAutoHideMenuBar(true) won't hide it immediately.

win.isMenuBarAutoHide()

Returns Boolean - Whether menu bar automatically hides itself.

win.setMenuBarVisibility(visible) Windows Linux

  • visible Boolean

Sets whether the menu bar should be visible. If the menu bar is auto-hide, users can still bring up the menu bar by pressing the single Alt key.

win.isMenuBarVisible()

Returns Boolean - Whether the menu bar is visible.

win.setVisibleOnAllWorkspaces(visible)

  • visible Boolean

Sets whether the window should be visible on all workspaces.

Note: This API does nothing on Windows.

win.isVisibleOnAllWorkspaces()

Returns Boolean - Whether the window is visible on all workspaces.

Note: This API always returns false on Windows.

win.setIgnoreMouseEvents(ignore[, options])

  • ignore Boolean
  • options Object (optional)

    • forward Boolean (optional) macOS Windows - If true, forwards mouse move messages to Chromium, enabling mouse related events such as mouseleave. Only used when ignore is true. If ignore is false, forwarding is always disabled regardless of this value.

Makes the window ignore all mouse events.

All mouse events happened in this window will be passed to the window below this window, but if this window has focus, it will still receive keyboard events.

win.setContentProtection(enable) macOS Windows

  • enable Boolean

Prevents the window contents from being captured by other apps.

On macOS it sets the NSWindow's sharingType to NSWindowSharingNone. On Windows it calls SetWindowDisplayAffinity with WDA_MONITOR.

win.setFocusable(focusable) Windows

  • focusable Boolean

Changes whether the window can be focused.

win.setParentWindow(parent) Linux macOS

  • parent BrowserWindow

Sets parent as current window's parent window, passing null will turn current window into a top-level window.

win.getParentWindow()

Returns BrowserWindow - The parent window.

win.getChildWindows()

Returns BrowserWindow[] - All child windows.

win.setAutoHideCursor(autoHide) macOS

  • autoHide Boolean

Controls whether to hide cursor when typing.

win.selectPreviousTab() macOS

Selects the previous tab when native tabs are enabled and there are other tabs in the window.

win.selectNextTab() macOS

Selects the next tab when native tabs are enabled and there are other tabs in the window.

win.mergeAllWindows() macOS

Merges all windows into one window with multiple tabs when native tabs are enabled and there is more than one open window.

win.moveTabToNewWindow() macOS

Moves the current tab into a new window if native tabs are enabled and there is more than one tab in the current window.

win.toggleTabBar() macOS

Toggles the visibility of the tab bar if native tabs are enabled and there is only one tab in the current window.

win.addTabbedWindow(browserWindow) macOS

  • browserWindow BrowserWindow

Adds a window as a tab on this window, after the tab for the window instance.

win.setVibrancy(type) macOS

  • type String - Can be appearance-based, light, dark, titlebar, selection, menu, popover, sidebar, medium-light or ultra-dark. See the macOS documentation for more details.

Adds a vibrancy effect to the browser window. Passing null or an empty string will remove the vibrancy effect on the window.

win.setTouchBar(touchBar) macOS Experimental

  • touchBar TouchBar

Sets the touchBar layout for the current window. Specifying null or undefined clears the touch bar. This method only has an effect if the machine has a touch bar and is running on macOS 10.12.1+.

Note: The TouchBar API is currently experimental and may change or be removed in future Electron releases.

win.getBrowserView() Experimental

Returns BrowserView | null - an attached BrowserView. Returns null if none is attached.

Note: The BrowserView API is currently experimental and may change or be removed in future Electron releases.


Class: BrowserWindowProxy

Manipulate the child browser window

Process: Renderer

The BrowserWindowProxy object is returned from window.open and provides limited functionality with the child window.

Instance Methods

The BrowserWindowProxy object has the following instance methods:

win.blur()

Removes focus from the child window.

win.close()

Forcefully closes the child window without calling its unload event.

win.eval(code)

  • code String

Evaluates the code in the child window.

win.focus()

Focuses the child window (brings the window to front).

win.print()

Invokes the print dialog on the child window.

win.postMessage(message, targetOrigin)

  • message String
  • targetOrigin String

Sends a message to the child window with the specified origin or * for no origin preference.

In addition to these methods, the child window implements window.opener object with no properties and a single method.

Instance Properties

The BrowserWindowProxy object has the following instance properties:

win.closed

A Boolean that is set to true after the child window gets closed.


Build Instructions

Follow the guidelines below for building Electron.

Platform prerequisites

Check the build prerequisites for your platform before proceeding

GN prerequisites

You'll need to install depot_tools, the toolset used for fetching Chromium and its dependencies.

Also, on Windows, you'll need to set the environment variable DEPOT_TOOLS_WIN_TOOLCHAIN=0. To do so, open Control PanelSystem and SecuritySystemAdvanced system settings and add a system variable DEPOT_TOOLS_WIN_TOOLCHAIN with value 0. This tells depot_tools to use your locally installed version of Visual Studio (by default, depot_tools will try to download a Google-internal version that only Googlers have access to).

GIT_CACHE_PATH

If you plan on building Electron more than once, adding a git cache will speed up subsequent calls to gclient. To do this, set a GIT_CACHE_PATH environment variable:

$ export GIT_CACHE_PATH="${HOME}/.git_cache"
$ mkdir -p "${GIT_CACHE_PATH}"
# This will use about 16G.

NOTE: the git cache will set the origin of the src/electron repository to point to the local cache, instead of the upstream git repository. This is undesirable when running git push—you probably want to push to github, not your local cache. To fix this, from the src/electron directory, run:

$ git remote set-url origin https://github.com/electron/electron

sccache

Thousands of files must be compiled to build Chromium and Electron. You can avoid much of the wait by reusing Electron CI's build output via sccache. This requires some optional steps (listed below) and these two environment variables:

export SCCACHE_BUCKET="electronjs-sccache"
export SCCACHE_TWO_TIER=true

Getting the code

$ mkdir electron-gn && cd electron-gn
$ gclient config \
    --name "src/electron" \
    --unmanaged \
    https://github.com/electron/electron
$ gclient sync --with_branch_heads --with_tags
# This will take a while, go get a coffee.

Instead of https://github.com/electron/electron, you can use your own fork here (something like https://github.com/<username>/electron).

A note on pulling/pushing

If you intend to git pull or git push from the official electron repository in the future, you now need to update the respective folder's origin URLs.

$ cd src/electron
$ git remote remove origin
$ git remote add origin https://github.com/electron/electron
$ git branch --set-upstream-to=origin/master
$ cd -

📝 gclient works by checking a file called DEPS inside the src/electron folder for dependencies (like Chromium or Node.js). Running gclient sync -f ensures that all dependencies required to build Electron match that file.

So, in order to pull, you'd run the following commands:

$ cd src/electron
$ git pull
$ gclient sync -f

Building

$ cd src
$ export CHROMIUM_BUILDTOOLS_PATH=`pwd`/buildtools
# this next line is needed only if building with sccache
$ export GN_EXTRA_ARGS="${GN_EXTRA_ARGS} cc_wrapper=\"${PWD}/electron/external_binaries/sccache\""
$ gn gen out/Debug --args="import(\"//electron/build/args/debug.gn\") $GN_EXTRA_ARGS"

Or on Windows (without the optional argument):

$ cd src
$ set CHROMIUM_BUILDTOOLS_PATH=%cd%\buildtools
$ gn gen out/Debug --args="import(\"//electron/build/args/debug.gn\")"

This will generate a build directory out/Debug under src/ with debug build configuration. You can replace Debug with another name, but it should be a subdirectory of out. Also you shouldn't have to run gn gen again—if you want to change the build arguments, you can run gn args out/Debug to bring up an editor.

To see the list of available build configuration options, run gn args out/Debug --list.

For generating Debug (aka "component" or "shared") build config of Electron:

$ gn gen out/Debug --args="import(\"//electron/build/args/debug.gn\") $GN_EXTRA_ARGS"

For generating Release (aka "non-component" or "static") build config of Electron:

$ gn gen out/Release --args="import(\"//electron/build/args/release.gn\") $GN_EXTRA_ARGS"

To build, run ninja with the electron target: Nota Bene: This will also take a while and probably heat up your lap.

For the debug configuration:

$ ninja -C out/Debug electron

For the release configuration:

$ ninja -C out/Release electron

This will build all of what was previously 'libchromiumcontent' (i.e. the content/ directory of chromium and its dependencies, incl. WebKit and V8), so it will take a while.

To speed up subsequent builds, you can use sccache. Add the GN arg cc_wrapper = "sccache" by running gn args out/Debug to bring up an editor and adding a line to the end of the file.

The built executable will be under ./out/Debug:

$ ./out/Debug/Electron.app/Contents/MacOS/Electron
# or, on Windows
$ ./out/Debug/electron.exe
# or, on Linux
$ ./out/Debug/electron

Cross-compiling

To compile for a platform that isn't the same as the one you're building on, set the target_cpu and target_os GN arguments. For example, to compile an x86 target from an x64 host, specify target_cpu = "x86" in gn args.

$ gn gen out/Debug-x86 --args='... target_cpu = "x86"'

Not all combinations of source and target CPU/OS are supported by Chromium. Only cross-compiling Windows 32-bit from Windows 64-bit and Linux 32-bit from Linux 64-bit have been tested in Electron. If you test other combinations and find them to work, please update this document :)

See the GN reference for allowable values of target_os and target_cpu

Tests

To run the tests, you'll first need to build the test modules against the same version of Node.js that was built as part of the build process. To generate build headers for the modules to compile against, run the following under src/ directory.

$ ninja -C out/Debug third_party/electron_node:headers
# Install the test modules with the generated headers
$ (cd electron/spec && npm i --nodedir=../../out/Debug/gen/node_headers)

Then, run Electron with electron/spec as the argument:

# on Mac:
$ ./out/Debug/Electron.app/Contents/MacOS/Electron electron/spec
# on Windows:
$ ./out/Debug/electron.exe electron/spec
# on Linux:
$ ./out/Debug/electron electron/spec

If you're debugging something, it can be helpful to pass some extra flags to the Electron binary:

$ ./out/Debug/Electron.app/Contents/MacOS/Electron electron/spec \
  --ci --enable-logging -g 'BrowserWindow module'

Sharing the git cache between multiple machines

It is possible to share the gclient git cache with other machines by exporting it as SMB share on linux, but only one process/machine can be using the cache at a time. The locks created by git-cache script will try to prevent this, but it may not work perfectly in a network.

On Windows, SMBv2 has a directory cache that will cause problems with the git cache script, so it is necessary to disable it by setting the registry key

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Lanmanworkstation\Parameters\DirectoryCacheLifetime

to 0. More information: https://stackoverflow.com/a/9935126

Stale locks in the git cache

If gclient sync is interrupted while using the git cache, it will leave the cache locked. To remove the lock, pass the --break_repo_locks argument to gclient sync.

I'm being asked for a username/password for chromium-internal.googlesource.com

If you see a prompt for Username for 'https://chrome-internal.googlesource.com': when running gclient sync on Windows, it's probably because the DEPOT_TOOLS_WIN_TOOLCHAIN environment variable is not set to 0. Open Control PanelSystem and SecuritySystemAdvanced system settings and add a system variable DEPOT_TOOLS_WIN_TOOLCHAIN with value 0. This tells depot_tools to use your locally installed version of Visual Studio (by default, depot_tools will try to download a Google-internal version that only Googlers have access to).


Build Instructions (Linux)

Follow the guidelines below for building Electron on Linux.

Prerequisites

  • At least 25GB disk space and 8GB RAM.

  • Python 2.7.x. Some distributions like CentOS 6.x still use Python 2.6.x so you may need to check your Python version with python -V.

    Please also ensure that your system and Python version support at least TLS 1.2. For a quick test, run the following script:

    $ npm run check-tls

    If the script returns that your configuration is using an outdated security protocol, use your system's package manager to update Python to the latest version in the 2.7.x branch. Alternatively, visit https://www.python.org/downloads/ for detailed instructions.

  • Node.js. There are various ways to install Node. You can download source code from nodejs.org and compile it. Doing so permits installing Node on your own home directory as a standard user. Or try repositories such as NodeSource.

  • clang 3.4 or later.

  • Development headers of GTK+ and libnotify.

On Ubuntu, install the following libraries:

$ sudo apt-get install build-essential clang libdbus-1-dev libgtk-3-dev \
                       libnotify-dev libgnome-keyring-dev libgconf2-dev \
                       libasound2-dev libcap-dev libcups2-dev libxtst-dev \
                       libxss1 libnss3-dev gcc-multilib g++-multilib curl \
                       gperf bison python-dbusmock

On RHEL / CentOS, install the following libraries:

$ sudo yum install clang dbus-devel gtk3-devel libnotify-devel \
                   libgnome-keyring-devel xorg-x11-server-utils libcap-devel \
                   cups-devel libXtst-devel alsa-lib-devel libXrandr-devel \
                   GConf2-devel nss-devel python-dbusmock

On Fedora, install the following libraries:

$ sudo dnf install clang dbus-devel gtk3-devel libnotify-devel \
                   libgnome-keyring-devel xorg-x11-server-utils libcap-devel \
                   cups-devel libXtst-devel alsa-lib-devel libXrandr-devel \
                   GConf2-devel nss-devel python-dbusmock

Other distributions may offer similar packages for installation via package managers such as pacman. Or one can compile from source code.

Cross compilation

If you want to build for an arm target you should also install the following dependencies:

$ sudo apt-get install libc6-dev-armhf-cross linux-libc-dev-armhf-cross \
                       g++-arm-linux-gnueabihf

Similarly for arm64, install the following:

$ sudo apt-get install libc6-dev-arm64-cross linux-libc-dev-arm64-cross \
                       g++-aarch64-linux-gnu

And to cross-compile for arm or ia32 targets, you should pass the target_cpu parameter to gn gen:

$ gn gen out/Debug --args='import(...) target_cpu="arm"'

Error While Loading Shared Libraries: libtinfo.so.5

Prebuilt clang will try to link to libtinfo.so.5. Depending on the host architecture, symlink to appropriate libncurses:

$ sudo ln -s /usr/lib/libncurses.so.5 /usr/lib/libtinfo.so.5

Advanced topics

The default building configuration is targeted for major desktop Linux distributions. To build for a specific distribution or device, the following information may help you.

Using system clang instead of downloaded clang binaries

By default Electron is built with prebuilt clang binaries provided by the Chromium project. If for some reason you want to build with the clang installed in your system, you can specify the clang_base_path argument in the GN args.

For example if you installed clang under /usr/local/bin/clang:

$ gn gen out/Debug --args='import("//electron/build/args/debug.gn") clang_base_path = "/usr/local/bin"'

Using compilers other than clang

Building Electron with compilers other than clang is not supported.


Build Instructions (macOS)

Follow the guidelines below for building Electron on macOS.

Prerequisites

  • macOS >= 10.11.6
  • Xcode >= 8.2.1
  • node.js (external)
  • Python 2.7 with support for TLS 1.2

Python

Please also ensure that your system and Python version support at least TLS 1.2. This depends on both your version of macOS and Python. For a quick test, run:

$ npm run check-tls

If the script returns that your configuration is using an outdated security protocol, you can either update macOS to High Sierra or install a new version of Python 2.7.x. To upgrade Python, use Homebrew:

$ brew install python@2 && brew link python@2 --force

If you are using Python as provided by Homebrew, you also need to install the following Python modules:

macOS SDK

If you're developing Electron and don't plan to redistribute your custom Electron build, you may skip this section.

For certain features (e.g. pinch-zoom) to work properly, you must target the macOS 10.10 SDK.

Official Electron builds are built with Xcode 8.2.1, which does not contain the 10.10 SDK by default. To obtain it, first download and mount the Xcode 6.4 DMG.

Then, assuming that the Xcode 6.4 DMG has been mounted at /Volumes/Xcode and that your Xcode 8.2.1 install is at /Applications/Xcode.app, run:

cp -r /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/

You will also need to enable Xcode to build against the 10.10 SDK:

  • Open /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Info.plist
  • Set the MinimumSDKVersion to 10.10
  • Save the file

Build Instructions (Windows)

Follow the guidelines below for building Electron on Windows.

Prerequisites

  • Windows 10 / Server 2012 R2 or higher
  • Visual Studio 2017 15.7.2 or higher - download VS 2017 Community Edition for free
  • Python 2.7.10 or higher

    • Contrary to the depot_tools setup instructions linked below, you will need to use your locally installed Python with at least version 2.7.10 (with support for TLS 1.2). To do so, make sure that in PATH, your locally installed Python comes before the depot_tools folder. Right now depot_tools still comes with Python 2.7.6, which will cause the gclient command to fail (see https://crbug.com/868864).
    • Python for Windows (pywin32) Extensions is also needed in ordner to run the build process.
  • Node.js
  • Git
  • Debugging Tools for Windows of Windows SDK 10.0.15063.468 if you plan on creating a full distribution since symstore.exe is used for creating a symbol store from .pdb files.

    • Different versions of the SDK can be installed side by side. To install the SDK, open Visual Studio Installer, select ChangeIndividual Components, scroll down and select the appropriate Windows SDK to install. Another option would be to look at the Windows SDK and emulator archive and download the standalone version of the SDK respectively.
    • The SDK Debugging Tools must also be installed. If the Windows 10 SDK was installed via the Visual Studio installer, then they can be installed by going to: Control PanelProgramsPrograms and Features → Select the "Windows Software Development Kit" → ChangeChange → Check "Debugging Tools For Windows" → Change. Or, you can download the standalone SDK installer and use it to install the Debugging Tools.

If you don't currently have a Windows installation, dev.microsoftedge.com has timebombed versions of Windows that you can use to build Electron.

Building Electron is done entirely with command-line scripts and cannot be done with Visual Studio. You can develop Electron with any editor but support for building with Visual Studio will come in the future.

Note: Even though Visual Studio is not used for building, it's still required because we need the build toolchains it provides.

32bit Build

To build for the 32bit target, you need to pass target_cpu = "x86" as a GN arg. You can build the 32bit target alongside the 64bit target by using a different output directory for GN, e.g. out/Release-x86, with different arguments.

$ gn gen out/Release-x86 --args="import(\"//electron/build/args/release.gn\") target_cpu=\"x86\""

The other building steps are exactly the same.

Visual Studio project

To generate a Visual Studio project, you can pass the --ide=vs2017 parameter to gn gen:

$ gn gen out/Debug --ide=vs2017

Command xxxx not found

If you encountered an error like Command xxxx not found, you may try to use the VS2015 Command Prompt console to execute the build scripts.

Fatal internal compiler error: C1001

Make sure you have the latest Visual Studio update installed.

LNK1181: cannot open input file 'kernel32.lib'

Try reinstalling 32bit Node.js.

Error: ENOENT, stat 'C:\Users\USERNAME\AppData\Roaming\npm'

Creating that directory should fix the problem:

$ mkdir ~\AppData\Roaming\npm

node-gyp is not recognized as an internal or external command

You may get this error if you are using Git Bash for building, you should use PowerShell or VS2015 Command Prompt instead.

cannot create directory at '...': Filename too long

node.js has some extremely long pathnames, and by default git on windows doesn't handle long pathnames correctly (even though windows supports them). This should fix it:

$ git config --system core.longpaths true

Build System Overview

Electron uses GN for project generation and ninja for building. Project configurations can be found in the .gn and .gni files.

GN Files

The following gn files contain the main rules for building Electron:

  • BUILD.gn defines how Electron itself is built and includes the default configurations for linking with Chromium.
  • build/args/{debug,release,all}.gn contain the default build arguments for building Electron.

Component Build

Since Chromium is quite a large project, the final linking stage can take quite a few minutes, which makes it hard for development. In order to solve this, Chromium introduced the "component build", which builds each component as a separate shared library, making linking very quick but sacrificing file size and performance.

Electron inherits this build option from Chromium. In Debug builds, the binary will be linked to a shared library version of Chromium's components to achieve fast linking time; for Release builds, the binary will be linked to the static library versions, so we can have the best possible binary size and performance.

Tests

NB this section is out of date and contains information that is no longer relevant to the GN-built electron.

Test your changes conform to the project coding style using:

$ npm run lint

Test functionality using:

$ npm test

Whenever you make changes to Electron source code, you'll need to re-run the build before the tests:

$ npm run build && npm test

You can make the test suite run faster by isolating the specific test or block you're currently working on using Mocha's exclusive tests feature. Append .only to any describe or it function call:

describe.only('some feature', function () {
  // ... only tests in this block will be run
})

Alternatively, you can use mocha's grep option to only run tests matching the given regular expression pattern:

$ npm test -- --grep child_process

Tests that include native modules (e.g. runas) can't be executed with the debug build (see #2558 for details), but they will work with the release build.

To run the tests with the release build use:

$ npm test -- -R

Certificate Object

  • data String - PEM encoded data
  • issuer CertificatePrincipal - Issuer principal
  • issuerName String - Issuer's Common Name
  • issuerCert Certificate - Issuer certificate (if not self-signed)
  • subject CertificatePrincipal - Subject principal
  • subjectName String - Subject's Common Name
  • serialNumber String - Hex value represented string
  • validStart Number - Start date of the certificate being valid in seconds
  • validExpiry Number - End date of the certificate being valid in seconds
  • fingerprint String - Fingerprint of the certificate

CertificatePrincipal Object

  • commonName String - Common Name
  • organizations String[] - Organization names
  • organizationUnits String[] - Organization Unit names
  • locality String - Locality
  • state String - State or province
  • country String - Country or region

Supported Chrome Command Line Switches

Command line switches supported by Electron.

You can use app.commandLine.appendSwitch to append them in your app's main script before the ready event of the app module is emitted:

const {app} = require('electron')
app.commandLine.appendSwitch('remote-debugging-port', '8315')
app.commandLine.appendSwitch('host-rules', 'MAP * 127.0.0.1')

app.on('ready', () => {
  // Your code here
})

--ignore-connections-limit=domains

Ignore the connections limit for domains list separated by ,.

--disable-http-cache

Disables the disk cache for HTTP requests.

--disable-http2

Disable HTTP/2 and SPDY/3.1 protocols.

--lang

Set a custom locale.

--inspect=port and --inspect-brk=port

Debug-related flags, see the Debugging the Main Process guide for details.

--remote-debugging-port=port

Enables remote debugging over HTTP on the specified port.

--disk-cache-size=size

Forces the maximum disk space to be used by the disk cache, in bytes.

--js-flags=flags

Specifies the flags passed to the Node JS engine. It has to be passed when starting Electron if you want to enable the flags in the main process.

$ electron --js-flags="--harmony_proxies --harmony_collections" your-app

See the Node documentation or run node --help in your terminal for a list of available flags. Additionally, run node --v8-options to see a list of flags that specifically refer to Node's V8 JavaScript engine.

--proxy-server=address:port

Use a specified proxy server, which overrides the system setting. This switch only affects requests with HTTP protocol, including HTTPS and WebSocket requests. It is also noteworthy that not all proxy servers support HTTPS and WebSocket requests.

--proxy-bypass-list=hosts

Instructs Electron to bypass the proxy server for the given semi-colon-separated list of hosts. This flag has an effect only if used in tandem with --proxy-server.

For example:

const {app} = require('electron')
app.commandLine.appendSwitch('proxy-bypass-list', '<local>;*.google.com;*foo.com;1.2.3.4:5678')

Will use the proxy server for all hosts except for local addresses (localhost, 127.0.0.1 etc.), google.com subdomains, hosts that contain the suffix foo.com and anything at 1.2.3.4:5678.

--proxy-pac-url=url

Uses the PAC script at the specified url.

--no-proxy-server

Don't use a proxy server and always make direct connections. Overrides any other proxy server flags that are passed.

--host-rules=rules

A comma-separated list of rules that control how hostnames are mapped.

For example:

  • MAP * 127.0.0.1 Forces all hostnames to be mapped to 127.0.0.1
  • MAP *.google.com proxy Forces all google.com subdomains to be resolved to "proxy".
  • MAP test.com [::1]:77 Forces "test.com" to resolve to IPv6 loopback. Will also force the port of the resulting socket address to be 77.
  • MAP * baz, EXCLUDE www.google.com Remaps everything to "baz", except for "www.google.com".

These mappings apply to the endpoint host in a net request (the TCP connect and host resolver in a direct connection, and the CONNECT in an HTTP proxy connection, and the endpoint host in a SOCKS proxy connection).

--host-resolver-rules=rules

Like --host-rules but these rules only apply to the host resolver.

--auth-server-whitelist=url

A comma-separated list of servers for which integrated authentication is enabled.

For example:

--auth-server-whitelist='*example.com, *foobar.com, *baz'

then any url ending with example.com, foobar.com, baz will be considered for integrated authentication. Without * prefix the url has to match exactly.

--auth-negotiate-delegate-whitelist=url

A comma-separated list of servers for which delegation of user credentials is required. Without * prefix the url has to match exactly.

--ignore-certificate-errors

Ignores certificate related errors.

--ppapi-flash-path=path

Sets the path of the pepper flash plugin.

--ppapi-flash-version=version

Sets the version of the pepper flash plugin.

--log-net-log=path

Enables net log events to be saved and writes them to path.

--disable-renderer-backgrounding

Prevents Chromium from lowering the priority of invisible pages' renderer processes.

This flag is global to all renderer processes, if you only want to disable throttling in one window, you can take the hack of playing silent audio.

--enable-logging

Prints Chromium's logging into console.

This switch can not be used in app.commandLine.appendSwitch since it is parsed earlier than user's app is loaded, but you can set the ELECTRON_ENABLE_LOGGING environment variable to achieve the same effect.

--v=log_level

Gives the default maximal active V-logging level; 0 is the default. Normally positive values are used for V-logging levels.

This switch only works when --enable-logging is also passed.

--vmodule=pattern

Gives the per-module maximal V-logging levels to override the value given by --v. E.g. my_module=2,foo*=3 would change the logging level for all code in source files my_module.* and foo*.*.

Any pattern containing a forward or backward slash will be tested against the whole pathname and not only the module. E.g. */foo/bar/*=2 would change the logging level for all code in the source files under a foo/bar directory.

This switch only works when --enable-logging is also passed.


Chromium Development

A collection of resources for learning about Chromium and tracking its development

See also V8 Development


Using clang-format on C++ Code

clang-format is a tool to automatically format C/C++/Objective-C code, so that developers don't need to worry about style issues during code reviews.

It is highly recommended to format your changed C++ code before opening pull requests, which will save you and the reviewers' time.

You can install clang-format and git-clang-format via npm install -g clang-format.

To automatically format a file according to Electron C++ code style, run clang-format -i path/to/electron/file.cc. It should work on macOS/Linux/Windows.

The workflow to format your changed code:

  1. Make codes changes in Electron repository.
  2. Run git add your_changed_file.cc.
  3. Run git-clang-format, and you will probably see modifications in your_changed_file.cc, these modifications are generated from clang-format.
  4. Run git add your_changed_file.cc, and commit your change.
  5. Now the branch is ready to be opened as a pull request.

If you want to format the changed code on your latest git commit (HEAD), you can run git-clang-format HEAD~1. See git-clang-format -h for more details.

Editor Integration

You can also integrate clang-format directly into your favorite editors. For further guidance on setting up editor integration, see these pages:


Class: ClientRequest

Make HTTP/HTTPS requests.

Process: Main

ClientRequest implements the Writable Stream interface and is therefore an EventEmitter.

new ClientRequest(options)

  • options (Object | String) - If options is a String, it is interpreted as the request URL. If it is an object, it is expected to fully specify an HTTP request via the following properties:

    • method String (optional) - The HTTP request method. Defaults to the GET method.
    • url String (optional) - The request URL. Must be provided in the absolute form with the protocol scheme specified as http or https.
    • session Object (optional) - The Session instance with which the request is associated.
    • partition String (optional) - The name of the partition with which the request is associated. Defaults to the empty string. The session option prevails on partition. Thus if a session is explicitly specified, partition is ignored.
    • protocol String (optional) - The protocol scheme in the form 'scheme:'. Currently supported values are 'http:' or 'https:'. Defaults to 'http:'.
    • host String (optional) - The server host provided as a concatenation of the hostname and the port number 'hostname:port'.
    • hostname String (optional) - The server host name.
    • port Integer (optional) - The server's listening port number.
    • path String (optional) - The path part of the request URL.
    • redirect String (optional) - The redirect mode for this request. Should be one of follow, error or manual. Defaults to follow. When mode is error, any redirection will be aborted. When mode is manual the redirection will be deferred until request.followRedirect is invoked. Listen for the redirect event in this mode to get more details about the redirect request.

options properties such as protocol, host, hostname, port and path strictly follow the Node.js model as described in the URL module.

For instance, we could have created the same request to 'github.com' as follows:

const request = net.request({
  method: 'GET',
  protocol: 'https:',
  hostname: 'github.com',
  port: 443,
  path: '/'
})

Event: 'response'

Returns:

  • response IncomingMessage - An object representing the HTTP response message.

Event: 'login'

Returns:

  • authInfo Object

    • isProxy Boolean
    • scheme String
    • host String
    • port Integer
    • realm String
  • callback Function

    • username String
    • password String

Emitted when an authenticating proxy is asking for user credentials.

The callback function is expected to be called back with user credentials:

  • username String
  • password String
request.on('login', (authInfo, callback) => {
  callback('username', 'password')
})

Providing empty credentials will cancel the request and report an authentication error on the response object:

request.on('response', (response) => {
  console.log(`STATUS: ${response.statusCode}`);
  response.on('error', (error) => {
    console.log(`ERROR: ${JSON.stringify(error)}`)
  })
})
request.on('login', (authInfo, callback) => {
  callback()
})

Event: 'finish'

Emitted just after the last chunk of the request's data has been written into the request object.

Event: 'abort'

Emitted when the request is aborted. The abort event will not be fired if the request is already closed.

Event: 'error'

Returns:

  • error Error - an error object providing some information about the failure.

Emitted when the net module fails to issue a network request. Typically when the request object emits an error event, a close event will subsequently follow and no response object will be provided.

Event: 'close'

Emitted as the last event in the HTTP request-response transaction. The close event indicates that no more events will be emitted on either the request or response objects.

Event: 'redirect'

Returns:

  • statusCode Integer
  • method String
  • redirectUrl String
  • responseHeaders Object

Emitted when there is redirection and the mode is manual. Calling request.followRedirect will continue with the redirection.

request.chunkedEncoding

A Boolean specifying whether the request will use HTTP chunked transfer encoding or not. Defaults to false. The property is readable and writable, however it can be set only before the first write operation as the HTTP headers are not yet put on the wire. Trying to set the chunkedEncoding property after the first write will throw an error.

Using chunked encoding is strongly recommended if you need to send a large request body as data will be streamed in small chunks instead of being internally buffered inside Electron process memory.

request.setHeader(name, value)

  • name String - An extra HTTP header name.
  • value Object - An extra HTTP header value.

Adds an extra HTTP header. The header name will issued as it is without lowercasing. It can be called only before first write. Calling this method after the first write will throw an error. If the passed value is not a String, its toString() method will be called to obtain the final value.

request.getHeader(name)

  • name String - Specify an extra header name.

Returns Object - The value of a previously set extra header name.

request.removeHeader(name)

  • name String - Specify an extra header name.

Removes a previously set extra header name. This method can be called only before first write. Trying to call it after the first write will throw an error.

request.write(chunk[, encoding][, callback])

  • chunk (String | Buffer) - A chunk of the request body's data. If it is a string, it is converted into a Buffer using the specified encoding.
  • encoding String (optional) - Used to convert string chunks into Buffer objects. Defaults to 'utf-8'.
  • callback Function (optional) - Called after the write operation ends.

callback is essentially a dummy function introduced in the purpose of keeping similarity with the Node.js API. It is called asynchronously in the next tick after chunk content have been delivered to the Chromium networking layer. Contrary to the Node.js implementation, it is not guaranteed that chunk content have been flushed on the wire before callback is called.

Adds a chunk of data to the request body. The first write operation may cause the request headers to be issued on the wire. After the first write operation, it is not allowed to add or remove a custom header.

request.end([chunk][, encoding][, callback])

  • chunk (String | Buffer) (optional)
  • encoding String (optional)
  • callback Function (optional)

Sends the last chunk of the request data. Subsequent write or end operations will not be allowed. The finish event is emitted just after the end operation.

request.abort()

Cancels an ongoing HTTP transaction. If the request has already emitted the close event, the abort operation will have no effect. Otherwise an ongoing event will emit abort and close events. Additionally, if there is an ongoing response object,it will emit the aborted event.

request.followRedirect()

Continues any deferred redirection request when the redirection mode is manual.

request.getUploadProgress()

Returns Object:

  • active Boolean - Whether the request is currently active. If this is false no other properties will be set
  • started Boolean - Whether the upload has started. If this is false both current and total will be set to 0.
  • current Integer - The number of bytes that have been uploaded so far
  • total Integer - The number of bytes that will be uploaded this request

You can use this method in conjunction with POST requests to get the progress of a file upload or other data transfer.


clipboard

Perform copy and paste operations on the system clipboard.

Process: Main, Renderer

The following example shows how to write a string to the clipboard:

const {clipboard} = require('electron')
clipboard.writeText('Example String')

On X Window systems, there is also a selection clipboard. To manipulate it you need to pass selection to each method:

const {clipboard} = require('electron')
clipboard.writeText('Example String', 'selection')
console.log(clipboard.readText('selection'))

Methods

The clipboard module has the following methods:

Note: Experimental APIs are marked as such and could be removed in future.

clipboard.readText([type])

  • type String (optional)

Returns String - The content in the clipboard as plain text.

clipboard.writeText(text[, type])

  • text String
  • type String (optional)

Writes the text into the clipboard as plain text.

clipboard.readHTML([type])

  • type String (optional)

Returns String - The content in the clipboard as markup.

clipboard.writeHTML(markup[, type])

  • markup String
  • type String (optional)

Writes markup to the clipboard.

clipboard.readImage([type])

  • type String (optional)

Returns NativeImage - The image content in the clipboard.

clipboard.writeImage(image[, type])

Writes image to the clipboard.

clipboard.readRTF([type])

  • type String (optional)

Returns String - The content in the clipboard as RTF.

clipboard.writeRTF(text[, type])

  • text String
  • type String (optional)

Writes the text into the clipboard in RTF.

clipboard.readBookmark() macOS Windows

Returns Object:

  • title String
  • url String

Returns an Object containing title and url keys representing the bookmark in the clipboard. The title and url values will be empty strings when the bookmark is unavailable.

clipboard.writeBookmark(title, url[, type]) macOS Windows

  • title String
  • url String
  • type String (optional)

Writes the title and url into the clipboard as a bookmark.

Note: Most apps on Windows don't support pasting bookmarks into them so you can use clipboard.write to write both a bookmark and fallback text to the clipboard.

clipboard.write({
  text: 'https://electronjs.org',
  bookmark: 'Electron Homepage'
})

clipboard.readFindText() macOS

Returns String - The text on the find pasteboard. This method uses synchronous IPC when called from the renderer process. The cached value is reread from the find pasteboard whenever the application is activated.

clipboard.writeFindText(text) macOS

  • text String

Writes the text into the find pasteboard as plain text. This method uses synchronous IPC when called from the renderer process.

clipboard.clear([type])

  • type String (optional)

Clears the clipboard content.

clipboard.availableFormats([type])

  • type String (optional)

Returns String[] - An array of supported formats for the clipboard type.

clipboard.has(format[, type]) Experimental

  • format String
  • type String (optional)

Returns Boolean - Whether the clipboard supports the specified format.

const {clipboard} = require('electron')
console.log(clipboard.has('<p>selection</p>'))

clipboard.read(format) Experimental

  • format String

Returns String - Reads format type from the clipboard.

clipboard.readBuffer(format) Experimental

  • format String

Returns Buffer - Reads format type from the clipboard.

clipboard.writeBuffer(format, buffer[, type]) Experimental

  • format String
  • buffer Buffer
  • type String (optional)

Writes the buffer into the clipboard as format.

clipboard.write(data[, type])

  • data Object

    • text String (optional)
    • html String (optional)
    • image NativeImage (optional)
    • rtf String (optional)
    • bookmark String (optional) - The title of the url at text.
  • type String (optional)
const {clipboard} = require('electron')
clipboard.write({text: 'test', html: '<b>test</b>'})

Writes data to the clipboard.


Code Signing

Code signing is a security technology that you use to certify that an app was created by you.

On macOS the system can detect any change to the app, whether the change is introduced accidentally or by malicious code.

On Windows the system assigns a trust level to your code signing certificate which if you don't have, or if your trust level is low will cause security dialogs to appear when users start using your application. Trust level builds over time so it's better to start code signing as early as possible.

While it is possible to distribute unsigned apps, it is not recommended. For example, here's what macOS users see when attempting to start an unsigned app:

unsigned app warning on macOS

App can't be opened because it is from an unidentified developer

If you are building an Electron app that you intend to package and distribute, it should be code signed. The Mac and Windows app stores do not allow unsigned apps.

Signing macOS builds

Before signing macOS builds, you must do the following:

  1. Enroll in the Apple Developer Program (requires an annual fee)
  2. Download and install Xcode
  3. Generate, download, and install signing certificates

There are a number of tools for signing your packaged app:

For more info, see the Mac App Store Submission Guide.

Signing Windows builds

Before signing Windows builds, you must do the following:

  1. Get a Windows Authenticode code signing certificate
  2. Install Visual Studio 2015/2017 (to get the signing utility)

You can get a code signing certificate from a lot of resellers, popular ones include:

  • digicert
  • Comodo
  • GoDaddy
  • Amongst others, please shop around to find one that suits your needs, Google is your friend :)

There are a number of tools for signing your packaged app:


Coding Style

These are the style guidelines for coding in Electron.

You can run npm run lint to show any style issues detected by cpplint and eslint.

General Code

  • End files with a newline.
  • Place requires in the following order:

    • Built in Node Modules (such as path)
    • Built in Electron Modules (such as ipc, app)
    • Local Modules (using relative paths)
  • Place class properties in the following order:

    • Class methods and properties (methods starting with a @)
    • Instance methods and properties
  • Avoid platform-dependent code:

    • Use path.join() to concatenate filenames.
    • Use os.tmpdir() rather than /tmp when you need to reference the temporary directory.
  • Using a plain return when returning explicitly at the end of a function.

    • Not return null, return undefined, null or undefined

C++ and Python

For C++ and Python, we follow Chromium's Coding Style. You can use clang-format to format the C++ code automatically. There is also a script script/cpplint.py to check whether all files conform.

The Python version we are using now is Python 2.7.

The C++ code uses a lot of Chromium's abstractions and types, so it's recommended to get acquainted with them. A good place to start is Chromium's Important Abstractions and Data Structures document. The document mentions some special types, scoped types (that automatically release their memory when going out of scope), logging mechanisms etc.

Documentation

  • Write remark markdown style.

You can run npm run lint-docs to ensure that your documentation changes are formatted correctly.

JavaScript

  • Write standard JavaScript style.
  • File names should be concatenated with - instead of _, e.g. file-name.js rather than file_name.js, because in github/atom module names are usually in the module-name form. This rule only applies to .js files.
  • Use newer ES6/ES2015 syntax where appropriate

Naming Things

Electron APIs uses the same capitalization scheme as Node.js:

  • When the module itself is a class like BrowserWindow, use PascalCase.
  • When the module is a set of APIs, like globalShortcut, use camelCase.
  • When the API is a property of object, and it is complex enough to be in a separate chapter like win.webContents, use mixedCase.
  • For other non-module APIs, use natural titles, like <webview> Tag or Process Object.

When creating a new API, it is preferred to use getters and setters instead of jQuery's one-function style. For example, .getText() and .setText(text) are preferred to .text([text]). There is a discussion on this.


contentTracing

Collect tracing data from Chromium's content module for finding performance bottlenecks and slow operations.

Process: Main

This module does not include a web interface so you need to open chrome://tracing/ in a Chrome browser and load the generated file to view the result.

Note: You should not use this module until the ready event of the app module is emitted.

const {app, contentTracing} = require('electron')

app.on('ready', () => {
  const options = {
    categoryFilter: '*',
    traceOptions: 'record-until-full,enable-sampling'
  }

  contentTracing.startRecording(options, () => {
    console.log('Tracing started')

    setTimeout(() => {
      contentTracing.stopRecording('', (path) => {
        console.log('Tracing data recorded to ' + path)
      })
    }, 5000)
  })
})

Methods

The contentTracing module has the following methods:

contentTracing.getCategories(callback)

  • callback Function

    • categories String[]

Get a set of category groups. The category groups can change as new code paths are reached.

Once all child processes have acknowledged the getCategories request the callback is invoked with an array of category groups.

contentTracing.startRecording(options, callback)

  • options Object

    • categoryFilter String
    • traceOptions String
  • callback Function

Start recording on all processes.

Recording begins immediately locally and asynchronously on child processes as soon as they receive the EnableRecording request. The callback will be called once all child processes have acknowledged the startRecording request.

categoryFilter is a filter to control what category groups should be traced. A filter can have an optional - prefix to exclude category groups that contain a matching category. Having both included and excluded category patterns in the same list is not supported.

Examples:

  • test_MyTest*,
  • test_MyTest*,test_OtherStuff,
  • "-excluded_category1,-excluded_category2

traceOptions controls what kind of tracing is enabled, it is a comma-delimited list. Possible options are:

  • record-until-full
  • record-continuously
  • trace-to-console
  • enable-sampling
  • enable-systrace

The first 3 options are trace recording modes and hence mutually exclusive. If more than one trace recording modes appear in the traceOptions string, the last one takes precedence. If none of the trace recording modes are specified, recording mode is record-until-full.

The trace option will first be reset to the default option (record_mode set to record-until-full, enable_sampling and enable_systrace set to false) before options parsed from traceOptions are applied on it.

contentTracing.stopRecording(resultFilePath, callback)

  • resultFilePath String
  • callback Function

    • resultFilePath String

Stop recording on all processes.

Child processes typically cache trace data and only rarely flush and send trace data back to the main process. This helps to minimize the runtime overhead of tracing since sending trace data over IPC can be an expensive operation. So, to end tracing, we must asynchronously ask all child processes to flush any pending trace data.

Once all child processes have acknowledged the stopRecording request, callback will be called with a file that contains the traced data.

Trace data will be written into resultFilePath if it is not empty or into a temporary file. The actual file path will be passed to callback if it's not null.

contentTracing.startMonitoring(options, callback)

  • options Object

    • categoryFilter String
    • traceOptions String
  • callback Function

Start monitoring on all processes.

Monitoring begins immediately locally and asynchronously on child processes as soon as they receive the startMonitoring request.

Once all child processes have acknowledged the startMonitoring request the callback will be called.

contentTracing.stopMonitoring(callback)

  • callback Function

Stop monitoring on all processes.

Once all child processes have acknowledged the stopMonitoring request the callback is called.

contentTracing.captureMonitoringSnapshot(resultFilePath, callback)

  • resultFilePath String
  • callback Function

    • resultFilePath String

Get the current monitoring traced data.

Child processes typically cache trace data and only rarely flush and send trace data back to the main process. This is because it may be an expensive operation to send the trace data over IPC and we would like to avoid unneeded runtime overhead from tracing. So, to end tracing, we must asynchronously ask all child processes to flush any pending trace data.

Once all child processes have acknowledged the captureMonitoringSnapshot request the callback will be called with a file that contains the traced data.

contentTracing.getTraceBufferUsage(callback)

  • callback Function

    • value Number
    • percentage Number

Get the maximum usage across processes of trace buffer as a percentage of the full state. When the TraceBufferUsage value is determined the callback is called.


Cookie Object

  • name String - The name of the cookie.
  • value String - The value of the cookie.
  • domain String (optional) - The domain of the cookie.
  • hostOnly Boolean (optional) - Whether the cookie is a host-only cookie.
  • path String (optional) - The path of the cookie.
  • secure Boolean (optional) - Whether the cookie is marked as secure.
  • httpOnly Boolean (optional) - Whether the cookie is marked as HTTP only.
  • session Boolean (optional) - Whether the cookie is a session cookie or a persistent cookie with an expiration date.
  • expirationDate Double (optional) - The expiration date of the cookie as the number of seconds since the UNIX epoch. Not provided for session cookies.

Class: Cookies

Query and modify a session's cookies.

Process: Main

Instances of the Cookies class are accessed by using cookies property of a Session.

For example:

const {session} = require('electron')

// Query all cookies.
session.defaultSession.cookies.get({}, (error, cookies) => {
  console.log(error, cookies)
})

// Query all cookies associated with a specific url.
session.defaultSession.cookies.get({url: 'http://www.github.com'}, (error, cookies) => {
  console.log(error, cookies)
})

// Set a cookie with the given cookie data;
// may overwrite equivalent cookies if they exist.
const cookie = {url: 'http://www.github.com', name: 'dummy_name', value: 'dummy'}
session.defaultSession.cookies.set(cookie, (error) => {
  if (error) console.error(error)
})

Instance Events

The following events are available on instances of Cookies:

Event: 'changed'

  • event Event
  • cookie Cookie - The cookie that was changed.
  • cause String - The cause of the change with one of the following values:

    • explicit - The cookie was changed directly by a consumer's action.
    • overwrite - The cookie was automatically removed due to an insert operation that overwrote it.
    • expired - The cookie was automatically removed as it expired.
    • evicted - The cookie was automatically evicted during garbage collection.
    • expired-overwrite - The cookie was overwritten with an already-expired expiration date.
  • removed Boolean - true if the cookie was removed, false otherwise.

Emitted when a cookie is changed because it was added, edited, removed, or expired.

Instance Methods

The following methods are available on instances of Cookies:

cookies.get(filter, callback)

  • filter Object

    • url String (optional) - Retrieves cookies which are associated with url. Empty implies retrieving cookies of all urls.
    • name String (optional) - Filters cookies by name.
    • domain String (optional) - Retrieves cookies whose domains match or are subdomains of domains.
    • path String (optional) - Retrieves cookies whose path matches path.
    • secure Boolean (optional) - Filters cookies by their Secure property.
    • session Boolean (optional) - Filters out session or persistent cookies.
  • callback Function

    • error Error
    • cookies Cookie[] - an array of cookie objects.

Sends a request to get all cookies matching filter, callback will be called with callback(error, cookies) on complete.

cookies.set(details, callback)

  • details Object

    • url String - The url to associate the cookie with.
    • name String (optional) - The name of the cookie. Empty by default if omitted.
    • value String (optional) - The value of the cookie. Empty by default if omitted.
    • domain String (optional) - The domain of the cookie. Empty by default if omitted.
    • path String (optional) - The path of the cookie. Empty by default if omitted.
    • secure Boolean (optional) - Whether the cookie should be marked as Secure. Defaults to false.
    • httpOnly Boolean (optional) - Whether the cookie should be marked as HTTP only. Defaults to false.
    • expirationDate Double (optional) - The expiration date of the cookie as the number of seconds since the UNIX epoch. If omitted then the cookie becomes a session cookie and will not be retained between sessions.
  • callback Function

    • error Error

Sets a cookie with details, callback will be called with callback(error) on complete.

cookies.remove(url, name, callback)

  • url String - The URL associated with the cookie.
  • name String - The name of cookie to remove.
  • callback Function

Removes the cookies matching url and name, callback will called with callback() on complete.

cookies.flushStore(callback)

  • callback Function

Writes any unwritten cookies data to disk.


CPUUsage Object

  • percentCPUUsage Number - Percentage of CPU used since the last call to getCPUUsage. First call returns 0.
  • idleWakeupsPerSecond Number - The number of average idle cpu wakeups per second since the last call to getCPUUsage. First call returns 0. Will always return 0 on Windows.

CrashReport Object

  • date Date
  • id String

crashReporter

Submit crash reports to a remote server.

Process: Main, Renderer

The following is an example of automatically submitting a crash report to a remote server:

const {crashReporter} = require('electron')

crashReporter.start({
  productName: 'YourName',
  companyName: 'YourCompany',
  submitURL: 'https://your-domain.com/url-to-submit',
  uploadToServer: true
})

For setting up a server to accept and process crash reports, you can use following projects:

Or use a 3rd party hosted solution:

Crash reports are saved locally in an application-specific temp directory folder. For a productName of YourName, crash reports will be stored in a folder named YourName Crashes inside the temp directory. You can customize this temp directory location for your app by calling the app.setPath('temp', '/my/custom/temp') API before starting the crash reporter.

Methods

The crashReporter module has the following methods:

crashReporter.start(options)

  • options Object

    • companyName String (optional)
    • submitURL String - URL that crash reports will be sent to as POST.
    • productName String (optional) - Defaults to app.getName().
    • uploadToServer Boolean (optional) - Whether crash reports should be sent to the server Default is true.
    • ignoreSystemCrashHandler Boolean (optional) - Default is false.
    • extra Object (optional) - An object you can define that will be sent along with the report. Only string properties are sent correctly. Nested objects are not supported and the property names and values must be less than 64 characters long.
    • crashesDirectory String (optional) - Directory to store the crashreports temporarily (only used when the crash reporter is started via process.crashReporter.start).

You are required to call this method before using any other crashReporter APIs and in each process (main/renderer) from which you want to collect crash reports. You can pass different options to crashReporter.start when calling from different processes.

Note Child processes created via the child_process module will not have access to the Electron modules. Therefore, to collect crash reports from them, use process.crashReporter.start instead. Pass the same options as above along with an additional one called crashesDirectory that should point to a directory to store the crash reports temporarily. You can test this out by calling process.crash() to crash the child process.

Note: To collect crash reports from child process in Windows, you need to add this extra code as well. This will start the process that will monitor and send the crash reports. Replace submitURL, productName and crashesDirectory with appropriate values.

Note: If you need send additional/updated extra parameters after your first call start you can call addExtraParameter on macOS or call start again with the new/updated extra parameters on Linux and Windows.

 const args = [
   `--reporter-url=${submitURL}`,
   `--application-name=${productName}`,
   `--crashes-directory=${crashesDirectory}`
 ]
 const env = {
   ELECTRON_INTERNAL_CRASH_SERVICE: 1
 }
 spawn(process.execPath, args, {
   env: env,
   detached: true
 })

Note: On macOS, Electron uses a new crashpad client for crash collection and reporting. If you want to enable crash reporting, initializing crashpad from the main process using crashReporter.start is required regardless of which process you want to collect crashes from. Once initialized this way, the crashpad handler collects crashes from all processes. You still have to call crashReporter.start from the renderer or child process, otherwise crashes from them will get reported without companyName, productName or any of the extra information.

crashReporter.getLastCrashReport()

Returns CrashReport:

Returns the date and ID of the last crash report. If no crash reports have been sent or the crash reporter has not been started, null is returned.

crashReporter.getUploadedReports()

Returns CrashReport[]:

Returns all uploaded crash reports. Each report contains the date and uploaded ID.

crashReporter.getUploadToServer() Linux macOS

Returns Boolean - Whether reports should be submitted to the server. Set through the start method or setUploadToServer.

Note: This API can only be called from the main process.

crashReporter.setUploadToServer(uploadToServer) Linux macOS

  • uploadToServer Boolean macOS - Whether reports should be submitted to the server.

This would normally be controlled by user preferences. This has no effect if called before start is called.

Note: This API can only be called from the main process.

crashReporter.addExtraParameter(key, value) macOS

  • key String - Parameter key, must be less than 64 characters long.
  • value String - Parameter value, must be less than 64 characters long.

Set an extra parameter to be sent with the crash report. The values specified here will be sent in addition to any values set via the extra option when start was called. This API is only available on macOS, if you need to add/update extra parameters on Linux and Windows after your first call to start you can call start again with the updated extra options.

crashReporter.removeExtraParameter(key) macOS

  • key String - Parameter key, must be less than 64 characters long.

Remove a extra parameter from the current set of parameters so that it will not be sent with the crash report.

crashReporter.getParameters()

See all of the current parameters being passed to the crash reporter.

Crash Report Payload

The crash reporter will send the following data to the submitURL as a multipart/form-data POST:

  • ver String - The version of Electron.
  • platform String - e.g. 'win32'.
  • process_type String - e.g. 'renderer'.
  • guid String - e.g. '5e1286fc-da97-479e-918b-6bfb0c3d1c72'.
  • _version String - The version in package.json.
  • _productName String - The product name in the crashReporter options object.
  • prod String - Name of the underlying product. In this case Electron.
  • _companyName String - The company name in the crashReporter options object.
  • upload_file_minidump File - The crash report in the format of minidump.
  • All level one properties of the extra object in the crashReporter options object.

Debugging on Windows

If you experience crashes or issues in Electron that you believe are not caused by your JavaScript application, but instead by Electron itself, debugging can be a little bit tricky, especially for developers not used to native/C++ debugging. However, using Visual Studio, GitHub's hosted Electron Symbol Server, and the Electron source code, you can enable step-through debugging with breakpoints inside Electron's source code.

See also: There's a wealth of information on debugging Chromium, much of which also applies to Electron, on the Chromium developers site: Debugging Chromium on Windows.

Requirements

  • A debug build of Electron: The easiest way is usually building it yourself, using the tools and prerequisites listed in the build instructions for Windows. While you can attach to and debug Electron as you can download it directly, you will find that it is heavily optimized, making debugging substantially more difficult: The debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations.

  • Visual Studio with C++ Tools: The free community editions of Visual Studio 2013 and Visual Studio 2015 both work. Once installed, configure Visual Studio to use GitHub's Electron Symbol server. It will enable Visual Studio to gain a better understanding of what happens inside Electron, making it easier to present variables in a human-readable format.

  • ProcMon: The free SysInternals tool allows you to inspect a processes parameters, file handles, and registry operations.

Attaching to and Debugging Electron

To start a debugging session, open up PowerShell/CMD and execute your debug build of Electron, using the application to open as a parameter.

$ ./out/Debug/electron.exe ~/my-electron-app/

Setting Breakpoints

Then, open up Visual Studio. Electron is not built with Visual Studio and hence does not contain a project file - you can however open up the source code files "As File", meaning that Visual Studio will open them up by themselves. You can still set breakpoints - Visual Studio will automatically figure out that the source code matches the code running in the attached process and break accordingly.

Relevant code files can be found in ./atom/.

Attaching

You can attach the Visual Studio debugger to a running process on a local or remote computer. After the process is running, click Debug / Attach to Process (or press CTRL+ALT+P) to open the "Attach to Process" dialog box. You can use this capability to debug apps that are running on a local or remote computer, debug multiple processes simultaneously.

If Electron is running under a different user account, select the Show processes from all users check box. Notice that depending on how many BrowserWindows your app opened, you will see multiple processes. A typical one-window app will result in Visual Studio presenting you with two Electron.exe entries - one for the main process and one for the renderer process. Since the list only gives you names, there's currently no reliable way of figuring out which is which.

Which Process Should I Attach to?

Code executed within the main process (that is, code found in or eventually run by your main JavaScript file) as well as code called using the remote (require('electron').remote) will run inside the main process, while other code will execute inside its respective renderer process.

You can be attached to multiple programs when you are debugging, but only one program is active in the debugger at any time. You can set the active program in the Debug Location toolbar or the Processes window.

Using ProcMon to Observe a Process

While Visual Studio is fantastic for inspecting specific code paths, ProcMon's strength is really in observing everything your application is doing with the operating system - it captures File, Registry, Network, Process, and Profiling details of processes. It attempts to log all events occurring and can be quite overwhelming, but if you seek to understand what and how your application is doing to the operating system, it can be a valuable resource.

For an introduction to ProcMon's basic and advanced debugging features, go check out this video tutorial provided by Microsoft.


Class: Debugger

An alternate transport for Chrome's remote debugging protocol.

Process: Main

Chrome Developer Tools has a special binding available at JavaScript runtime that allows interacting with pages and instrumenting them.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()

try {
  win.webContents.debugger.attach('1.1')
} catch (err) {
  console.log('Debugger attach failed : ', err)
}

win.webContents.debugger.on('detach', (event, reason) => {
  console.log('Debugger detached due to : ', reason)
})

win.webContents.debugger.on('message', (event, method, params) => {
  if (method === 'Network.requestWillBeSent') {
    if (params.request.url === 'https://www.github.com') {
      win.webContents.debugger.detach()
    }
  }
})

win.webContents.debugger.sendCommand('Network.enable')

debugger.attach([protocolVersion])

  • protocolVersion String (optional) - Requested debugging protocol version.

Attaches the debugger to the webContents.

debugger.isAttached()

Returns Boolean - Whether a debugger is attached to the webContents.

debugger.detach()

Detaches the debugger from the webContents.

debugger.sendCommand(method[, commandParams, callback])

  • method String - Method name, should be one of the methods defined by the remote debugging protocol.
  • commandParams Object (optional) - JSON object with request parameters.
  • callback Function (optional) - Response

    • error Object - Error message indicating the failure of the command.
    • result Any - Response defined by the 'returns' attribute of the command description in the remote debugging protocol.

Send given command to the debugging target.

Event: 'detach'

  • event Event
  • reason String - Reason for detaching debugger.

Emitted when debugging session is terminated. This happens either when webContents is closed or devtools is invoked for the attached webContents.

Event: 'message'

  • event Event
  • method String - Method name.
  • params Object - Event parameters defined by the 'parameters' attribute in the remote debugging protocol.

Emitted whenever debugging target issues instrumentation event.


Debugging on macOS

If you experience crashes or issues in Electron that you believe are not caused by your JavaScript application, but instead by Electron itself, debugging can be a little bit tricky, especially for developers not used to native/C++ debugging. However, using lldb, and the Electron source code, you can enable step-through debugging with breakpoints inside Electron's source code. You can also use XCode for debugging if you prefer a graphical interface.

Requirements

  • A debug build of Electron: The easiest way is usually building it yourself, using the tools and prerequisites listed in the build instructions for macOS. While you can attach to and debug Electron as you can download it directly, you will find that it is heavily optimized, making debugging substantially more difficult: The debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations.

  • Xcode: In addition to Xcode, also install the Xcode command line tools. They include LLDB, the default debugger in Xcode on Mac OS X. It supports debugging C, Objective-C and C++ on the desktop and iOS devices and simulator.

Attaching to and Debugging Electron

To start a debugging session, open up Terminal and start lldb, passing a debug build of Electron as a parameter.

$ lldb ./out/Debug/Electron.app
(lldb) target create "./out/Debug/Electron.app"
Current executable set to './out/Debug/Electron.app' (x86_64).

Setting Breakpoints

LLDB is a powerful tool and supports multiple strategies for code inspection. For this basic introduction, let's assume that you're calling a command from JavaScript that isn't behaving correctly - so you'd like to break on that command's C++ counterpart inside the Electron source.

Relevant code files can be found in ./atom/.

Let's assume that you want to debug app.setName(), which is defined in browser.cc as Browser::SetName(). Set the breakpoint using the breakpoint command, specifying file and line to break on:

(lldb) breakpoint set --file browser.cc --line 117
Breakpoint 1: where = Electron Framework`atom::Browser::SetName(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) + 20 at browser.cc:118, address = 0x000000000015fdb4

Then, start Electron:

(lldb) run

The app will immediately be paused, since Electron sets the app's name on launch:

(lldb) run
Process 25244 launched: '/Users/fr/Code/electron/out/Debug/Electron.app/Contents/MacOS/Electron' (x86_64)
Process 25244 stopped
* thread #1: tid = 0x839a4c, 0x0000000100162db4 Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 20 at browser.cc:118, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x0000000100162db4 Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 20 at browser.cc:118
   115 	}
   116
   117 	void Browser::SetName(const std::string& name) {
-> 118 	  name_override_ = name;
   119 	}
   120
   121 	int Browser::GetBadgeCount() {
(lldb)

To show the arguments and local variables for the current frame, run frame variable (or fr v), which will show you that the app is currently setting the name to "Electron".

(lldb) frame variable
(atom::Browser *) this = 0x0000000108b14f20
(const string &) name = "Electron": {
    [...]
}

To do a source level single step in the currently selected thread, execute step (or s). This would take you into name_override_.empty(). To proceed and do a step over, run next (or n).

(lldb) step
Process 25244 stopped
* thread #1: tid = 0x839a4c, 0x0000000100162dcc Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 44 at browser.cc:119, queue = 'com.apple.main-thread', stop reason = step in
    frame #0: 0x0000000100162dcc Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 44 at browser.cc:119
   116
   117 	void Browser::SetName(const std::string& name) {
   118 	  name_override_ = name;
-> 119 	}
   120
   121 	int Browser::GetBadgeCount() {
   122 	  return badge_count_;

To finish debugging at this point, run process continue. You can also continue until a certain line is hit in this thread (thread until 100). This command will run the thread in the current frame till it reaches line 100 in this frame or stops if it leaves the current frame.

Now, if you open up Electron's developer tools and call setName, you will once again hit the breakpoint.

Further Reading

LLDB is a powerful tool with a great documentation. To learn more about it, consider Apple's debugging documentation, for instance the LLDB Command Structure Reference or the introduction to Using LLDB as a Standalone Debugger.

You can also check out LLDB's fantastic manual and tutorial, which will explain more complex debugging scenarios.


Generate xcode project for debugging sources (cannot build code from xcode)

Run gn gen with the --ide=xcode argument.

$ gn gen out/Debug --ide=xcode

This will generate the electron.ninja.xcworkspace. You will have to open this workspace to set breakpoints and inspect.

See gn help gen for more information on generating IDE projects with GN.

Debugging and breakpoints

Launch Electron app after build. You can now open the xcode workspace created above and attach to the Electron process through the Debug > Attach To Process > Electron debug menu. [Note: If you want to debug the renderer process, you need to attach to the Electron Helper as well.]

You can now set breakpoints in any of the indexed files. However, you will not be able to set breakpoints directly in the Chromium source. To set break points in the Chromium source, you can choose Debug > Breakpoints > Create Symbolic Breakpoint and set any function name as the symbol. This will set the breakpoint for all functions with that name, from all the classes if there are more than one. You can also do this step of setting break points prior to attaching the debugger, however, actual breakpoints for symbolic breakpoint functions may not show up until the debugger is attached to the app.


Debugging the Main Process

The DevTools in an Electron browser window can only debug JavaScript that's executed in that window (i.e. the web pages). To debug JavaScript that's executed in the main process you will need to use an external debugger and launch Electron with the --inspect or --inspect-brk switch.

Command Line Switches

Use one of the following command line switches to enable debugging of the main process:

--inspect=[port]

Electron will listen for V8 inspector protocol messages on the specified port, an external debugger will need to connect on this port. The default port is 5858.

electron --inspect=5858 your/app

--inspect-brk=[port]

Like --inspect but pauses execution on the first line of JavaScript.

External Debuggers

You will need to use a debugger that supports the V8 inspector protocol.


1. Open an Electron project in VSCode.

$ git clone git@github.com:electron/electron-quick-start.git
$ code electron-quick-start

2. Add a file .vscode/launch.json with the following configuration:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Debug Main Process",
      "type": "node",
      "request": "launch",
      "cwd": "${workspaceRoot}",
      "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron",
      "windows": {
        "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron.cmd"
      },
      "args" : ["."]
    }
  ]
}

3. Debugging

Set some breakpoints in main.js, and start debugging in the Debug View. You should be able to hit the breakpoints.

Here is a pre-configured project that you can download and directly debug in VSCode: https://github.com/octref/vscode-electron-debug/tree/master/electron-quick-start


desktopCapturer

Access information about media sources that can be used to capture audio and video from the desktop using the navigator.mediaDevices.getUserMedia API.

Process: Renderer

The following example shows how to capture video from a desktop window whose title is Electron:

// In the renderer process.
const {desktopCapturer} = require('electron')

desktopCapturer.getSources({types: ['window', 'screen']}, (error, sources) => {
  if (error) throw error
  for (let i = 0; i < sources.length; ++i) {
    if (sources[i].name === 'Electron') {
      navigator.mediaDevices.getUserMedia({
        audio: false,
        video: {
          mandatory: {
            chromeMediaSource: 'desktop',
            chromeMediaSourceId: sources[i].id,
            minWidth: 1280,
            maxWidth: 1280,
            minHeight: 720,
            maxHeight: 720
          }
        }
      })
      .then((stream) => handleStream(stream))
      .catch((e) => handleError(e))
      return
    }
  }
})

function handleStream (stream) {
  const video = document.querySelector('video')
  video.srcObject = stream
  video.onloadedmetadata = (e) => video.play()
}

function handleError (e) {
  console.log(e)
}

To capture video from a source provided by desktopCapturer the constraints passed to navigator.mediaDevices.getUserMedia must include chromeMediaSource: 'desktop', and audio: false.

To capture both audio and video from the entire desktop the constraints passed to navigator.mediaDevices.getUserMedia must include chromeMediaSource: 'desktop', for both audio and video, but should not include a chromeMediaSourceId constraint.

const constraints = {
  audio: {
    mandatory: {
      chromeMediaSource: 'desktop'
    }
  },
  video: {
    mandatory: {
      chromeMediaSource: 'desktop'
    }
  }
}

Methods

The desktopCapturer module has the following methods:

desktopCapturer.getSources(options, callback)

  • options Object

    • types String[] - An array of Strings that lists the types of desktop sources to be captured, available types are screen and window.
    • thumbnailSize Size (optional) - The size that the media source thumbnail should be scaled to. Default is 150 x 150.
  • callback Function

Starts gathering information about all available desktop media sources, and calls callback(error, sources) when finished.

sources is an array of DesktopCapturerSource objects, each DesktopCapturerSource represents a screen or an individual window that can be captured.


DesktopCapturerSource Object

  • id String - The identifier of a window or screen that can be used as a chromeMediaSourceId constraint when calling [navigator.webkitGetUserMedia]. The format of the identifier will be window:XX or screen:XX, where XX is a random generated number.
  • name String - A screen source will be named either Entire Screen or Screen <index>, while the name of a window source will match the window title.
  • thumbnail NativeImage - A thumbnail image. Note: There is no guarantee that the size of the thumbnail is the same as the thumbnailSize specified in the options passed to desktopCapturer.getSources. The actual size depends on the scale of the screen or window.
  • display_id String - A unique identifier that will correspond to the id of the matching Display returned by the Screen API. On some platforms, this is equivalent to the XX portion of the id field above and on others it will differ. It will be an empty string if not available.

Desktop Environment Integration

Different operating systems provide different features for integrating desktop applications into their desktop environments. For example, on Windows, applications can put shortcuts in the JumpList of task bar, and on Mac, applications can put a custom menu in the dock menu.

This guide explains how to integrate your application into those desktop environments with Electron APIs.


Developer Environment

Electron development is essentially Node.js development. To turn your operating system into an environment capable of building desktop apps with Electron, you will merely need Node.js, npm, a code editor of your choice, and a rudimentary understanding of your operating system's command line client.

Setting up macOS

Electron supports macOS 10.10 (Yosemite) and up. Apple does not allow running macOS in virtual machines unless the host computer is already an Apple computer, so if you find yourself in need of a Mac, consider using a cloud service that rents access to Macs (like MacInCloud or xcloud).

First, install a recent version of Node.js. We recommend that you install either the latest LTS or Current version available. Visit the Node.js download page and select the macOS Installer. While Homebrew is an offered option, but we recommend against it - many tools will be incompatible with the way Homebrew installs Node.js.

Once downloaded, execute the installer and let the installation wizard guide you through the installation.

Once installed, confirm that everything works as expected. Find the macOS Terminal application in your /Applications/Utilities folder (or by searching for the word Terminal in Spotlight). Open up Terminal or another command line client of your choice and confirm that both node and npm are available:

# This command should print the version of Node.js
node -v

# This command should print the version of npm
npm -v

If both commands printed a version number, you are all set! Before you get started, you might want to install a code editor suited for JavaScript development.

Setting up Windows

Electron supports Windows 7 and later versions – attempting to develop Electron applications on earlier versions of Windows will not work. Microsoft provides free virtual machine images with Windows 10 for developers.

First, install a recent version of Node.js. We recommend that you install either the latest LTS or Current version available. Visit the Node.js download page and select the Windows Installer. Once downloaded, execute the installer and let the installation wizard guide you through the installation.

On the screen that allows you to configure the installation, make sure to select the Node.js runtime, npm package manager, and Add to PATH options.

Once installed, confirm that everything works as expected. Find the Windows PowerShell by opening the Start Menu and typing PowerShell. Open up PowerShell or another command line client of your choice and confirm that both node and npm are available:

# This command should print the version of Node.js
node -v

# This command should print the version of npm
npm -v

If both commands printed a version number, you are all set! Before you get started, you might want to install a code editor suited for JavaScript development.

Setting up Linux

Generally speaking, Electron supports Ubuntu 12.04, Fedora 21, Debian 8 and later.

First, install a recent version of Node.js. Depending on your Linux distribution, the installation steps might differ. Assuming that you normally install software using a package manager like apt or pacman, use the official Node.js guidance on installing on Linux.

You're running Linux, so you likely already know how to operate a command line client. Open up your favorite client and confirm that both node and npm are available globally:

# This command should print the version of Node.js
node -v

# This command should print the version of npm
npm -v

If both commands printed a version number, you are all set! Before you get started, you might want to install a code editor suited for JavaScript development.

A Good Editor

We might suggest two free popular editors built in Electron: GitHub's Atom and Microsoft's Visual Studio Code. Both of them have excellent JavaScript support.

If you are one of the many developers with a strong preference, know that virtually all code editors and IDEs these days support JavaScript.


DevTools Extension

Electron supports the Chrome DevTools Extension, which can be used to extend the ability of devtools for debugging popular web frameworks.

How to load a DevTools Extension

This document outlines the process for manually loading an extension. You may also try electron-devtools-installer, a third-party tool that downloads extensions directly from the Chrome WebStore.

To load an extension in Electron, you need to download it in Chrome browser, locate its filesystem path, and then load it by calling the BrowserWindow.addDevToolsExtension(extension) API.

Using the React Developer Tools as example:

  1. Install it in Chrome browser.
  2. Navigate to chrome://extensions, and find its extension ID, which is a hash string like fmkadmapgofadopljbjfkapdkoienihi.
  3. Find out filesystem location used by Chrome for storing extensions:

    • on Windows it is %LOCALAPPDATA%\Google\Chrome\User Data\Default\Extensions;
    • on Linux it could be:

      • ~/.config/google-chrome/Default/Extensions/
      • ~/.config/google-chrome-beta/Default/Extensions/
      • ~/.config/google-chrome-canary/Default/Extensions/
      • ~/.config/chromium/Default/Extensions/
    • on macOS it is ~/Library/Application Support/Google/Chrome/Default/Extensions.
  4. Pass the location of the extension to BrowserWindow.addDevToolsExtension API, for the React Developer Tools, it is something like: ~/Library/Application Support/Google/Chrome/Default/Extensions/fmkadmapgofadopljbjfkapdkoienihi/0.15.0_0

Note: The BrowserWindow.addDevToolsExtension API cannot be called before the ready event of the app module is emitted.

The name of the extension is returned by BrowserWindow.addDevToolsExtension, and you can pass the name of the extension to the BrowserWindow.removeDevToolsExtension API to unload it.

Supported DevTools Extensions

Electron only supports a limited set of chrome.* APIs, so some extensions using unsupported chrome.* APIs for chrome extension features may not work. Following Devtools Extensions are tested and guaranteed to work in Electron:

What should I do if a DevTools Extension is not working?

First please make sure the extension is still being maintained, some extensions can not even work for recent versions of Chrome browser, and we are not able to do anything for them.

Then file a bug at Electron's issues list, and describe which part of the extension is not working as expected.


dialog

Display native system dialogs for opening and saving files, alerting, etc.

Process: Main

An example of showing a dialog to select multiple files and directories:

const {dialog} = require('electron')
console.log(dialog.showOpenDialog({properties: ['openFile', 'openDirectory', 'multiSelections']}))

The Dialog is opened from Electron's main thread. If you want to use the dialog object from a renderer process, remember to access it using the remote:

const {dialog} = require('electron').remote
console.log(dialog)

Methods

The dialog module has the following methods:

dialog.showOpenDialog([browserWindow, ]options[, callback])

  • browserWindow BrowserWindow (optional)
  • options Object

    • title String (optional)
    • defaultPath String (optional)
    • buttonLabel String (optional) - Custom label for the confirmation button, when left empty the default label will be used.
    • filters FileFilter[] (optional)
    • properties String - Contains which features the dialog should use. The following values are supported:

      • openFile - Allow files to be selected.
      • openDirectory - Allow directories to be selected.
      • multiSelections - Allow multiple paths to be selected.
      • showHiddenFiles - Show hidden files in dialog.
      • createDirectory macOS - Allow creating new directories from dialog.
      • promptToCreate Windows - Prompt for creation if the file path entered in the dialog does not exist. This does not actually create the file at the path but allows non-existent paths to be returned that should be created by the application.
      • noResolveAliases macOS - Disable the automatic alias (symlink) path resolution. Selected aliases will now return the alias path instead of their target path.
      • treatPackageAsDirectory macOS - Treat packages, such as .app folders, as a directory instead of a file.
    • message String (optional) macOS - Message to display above input boxes.
    • securityScopedBookmarks Boolean (optional) masOS mas - Create security scoped bookmarks when packaged for the Mac App Store.
  • callback Function (optional)

    • filePaths String[] - An array of file paths chosen by the user
    • bookmarks String[] macOS mas - An array matching the filePaths array of base64 encoded strings which contains security scoped bookmark data. securityScopedBookmarks must be enabled for this to be populated.

Returns String[], an array of file paths chosen by the user, if the callback is provided it returns undefined.

The browserWindow argument allows the dialog to attach itself to a parent window, making it modal.

The filters specifies an array of file types that can be displayed or selected when you want to limit the user to a specific type. For example:

{
  filters: [
    {name: 'Images', extensions: ['jpg', 'png', 'gif']},
    {name: 'Movies', extensions: ['mkv', 'avi', 'mp4']},
    {name: 'Custom File Type', extensions: ['as']},
    {name: 'All Files', extensions: ['*']}
  ]
}

The extensions array should contain extensions without wildcards or dots (e.g. 'png' is good but '.png' and '*.png' are bad). To show all files, use the '*' wildcard (no other wildcard is supported).

If a callback is passed, the API call will be asynchronous and the result will be passed via callback(filenames).

Note: On Windows and Linux an open dialog can not be both a file selector and a directory selector, so if you set properties to ['openFile', 'openDirectory'] on these platforms, a directory selector will be shown.

dialog.showSaveDialog([browserWindow, ]options[, callback])

  • browserWindow BrowserWindow (optional)
  • options Object

    • title String (optional)
    • defaultPath String (optional) - Absolute directory path, absolute file path, or file name to use by default.
    • buttonLabel String (optional) - Custom label for the confirmation button, when left empty the default label will be used.
    • filters FileFilter[] (optional)
    • message String (optional) macOS - Message to display above text fields.
    • nameFieldLabel String (optional) macOS - Custom label for the text displayed in front of the filename text field.
    • showsTagField Boolean (optional) macOS - Show the tags input box, defaults to true.
    • securityScopedBookmarks Boolean (optional) masOS mas - Create a security scoped bookmark when packaged for the Mac App Store. If this option is enabled and the file doesn't already exist a blank file will be created at the chosen path.
  • callback Function (optional)

    • filename String
    • bookmark String macOS mas - Base64 encoded string which contains the security scoped bookmark data for the saved file. securityScopedBookmarks must be enabled for this to be present.

Returns String, the path of the file chosen by the user, if a callback is provided it returns undefined.

The browserWindow argument allows the dialog to attach itself to a parent window, making it modal.

The filters specifies an array of file types that can be displayed, see dialog.showOpenDialog for an example.

If a callback is passed, the API call will be asynchronous and the result will be passed via callback(filename).

dialog.showMessageBox([browserWindow, ]options[, callback])

  • browserWindow BrowserWindow (optional)
  • options Object

    • type String (optional) - Can be "none", "info", "error", "question" or "warning". On Windows, "question" displays the same icon as "info", unless you set an icon using the "icon" option. On macOS, both "warning" and "error" display the same warning icon.
    • buttons String - Array of texts for buttons. On Windows, an empty array will result in one button labeled "OK".
    • defaultId Integer (optional) - Index of the button in the buttons array which will be selected by default when the message box opens.
    • title String (optional) - Title of the message box, some platforms will not show it.
    • message String - Content of the message box.
    • detail String (optional) - Extra information of the message.
    • checkboxLabel String (optional) - If provided, the message box will include a checkbox with the given label. The checkbox state can be inspected only when using callback.
    • checkboxChecked Boolean (optional) - Initial checked state of the checkbox. false by default.
    • icon NativeImage (optional)
    • cancelId Integer (optional) - The index of the button to be used to cancel the dialog, via the Esc key. By default this is assigned to the first button with "cancel" or "no" as the label. If no such labeled buttons exist and this option is not set, 0 will be used as the return value or callback response. This option is ignored on Windows.
    • noLink Boolean (optional) - On Windows Electron will try to figure out which one of the buttons are common buttons (like "Cancel" or "Yes"), and show the others as command links in the dialog. This can make the dialog appear in the style of modern Windows apps. If you don't like this behavior, you can set noLink to true.
    • normalizeAccessKeys Boolean (optional) - Normalize the keyboard access keys across platforms. Default is false. Enabling this assumes & is used in the button labels for the placement of the keyboard shortcut access key and labels will be converted so they work correctly on each platform, & characters are removed on macOS, converted to _ on Linux, and left untouched on Windows. For example, a button label of Vie&w will be converted to Vie_w on Linux and View on macOS and can be selected via Alt-W on Windows and Linux.
  • callback Function (optional)

    • response Number - The index of the button that was clicked.
    • checkboxChecked Boolean - The checked state of the checkbox if checkboxLabel was set. Otherwise false.

Returns Integer, the index of the clicked button, if a callback is provided it returns undefined.

Shows a message box, it will block the process until the message box is closed. It returns the index of the clicked button.

The browserWindow argument allows the dialog to attach itself to a parent window, making it modal.

If a callback is passed, the dialog will not block the process. The API call will be asynchronous and the result will be passed via callback(response).

dialog.showErrorBox(title, content)

  • title String - The title to display in the error box.
  • content String - The text content to display in the error box.

Displays a modal dialog that shows an error message.

This API can be called safely before the ready event the app module emits, it is usually used to report errors in early stage of startup. If called before the app readyevent on Linux, the message will be emitted to stderr, and no GUI dialog will appear.

dialog.showCertificateTrustDialog([browserWindow, ]options, callback) macOS Windows

  • browserWindow BrowserWindow (optional)
  • options Object

    • certificate Certificate - The certificate to trust/import.
    • message String - The message to display to the user.
  • callback Function

On macOS, this displays a modal dialog that shows a message and certificate information, and gives the user the option of trusting/importing the certificate. If you provide a browserWindow argument the dialog will be attached to the parent window, making it modal.

On Windows the options are more limited, due to the Win32 APIs used:

  • The message argument is not used, as the OS provides its own confirmation dialog.
  • The browserWindow argument is ignored since it is not possible to make this confirmation dialog modal.

Sheets

On macOS, dialogs are presented as sheets attached to a window if you provide a BrowserWindow reference in the browserWindow parameter, or modals if no window is provided.

You can call BrowserWindow.getCurrentWindow().setSheetOffset(offset) to change the offset from the window frame where sheets are attached.


Display Object

  • id Number - Unique identifier associated with the display.
  • rotation Number - Can be 0, 90, 180, 270, represents screen rotation in clock-wise degrees.
  • scaleFactor Number - Output device's pixel scale factor.
  • touchSupport String - Can be available, unavailable, unknown.
  • bounds Rectangle
  • size Size
  • workArea Rectangle
  • workAreaSize Size

The Display object represents a physical display connected to the system. A fake Display may exist on a headless system, or a Display may correspond to a remote, virtual display.


Class: DownloadItem

Control file downloads from remote sources.

Process: Main

DownloadItem is an EventEmitter that represents a download item in Electron. It is used in will-download event of Session class, and allows users to control the download item.

// In the main process.
const {BrowserWindow} = require('electron')
let win = new BrowserWindow()
win.webContents.session.on('will-download', (event, item, webContents) => {
  // Set the save path, making Electron not to prompt a save dialog.
  item.setSavePath('/tmp/save.pdf')

  item.on('updated', (event, state) => {
    if (state === 'interrupted') {
      console.log('Download is interrupted but can be resumed')
    } else if (state === 'progressing') {
      if (item.isPaused()) {
        console.log('Download is paused')
      } else {
        console.log(`Received bytes: ${item.getReceivedBytes()}`)
      }
    }
  })
  item.once('done', (event, state) => {
    if (state === 'completed') {
      console.log('Download successfully')
    } else {
      console.log(`Download failed: ${state}`)
    }
  })
})

Event: 'updated'

Returns:

  • event Event
  • state String - Can be progressing or interrupted.

Emitted when the download has been updated and is not done.

The state can be one of following:

  • progressing - The download is in-progress.
  • interrupted - The download has interrupted and can be resumed.

Event: 'done'

Returns:

  • event Event
  • state String - Can be completed, cancelled or interrupted.

Emitted when the download is in a terminal state. This includes a completed download, a cancelled download (via downloadItem.cancel()), and interrupted download that can't be resumed.

The state can be one of following:

  • completed - The download completed successfully.
  • cancelled - The download has been cancelled.
  • interrupted - The download has interrupted and can not resume.

Instance Methods

The downloadItem object has the following methods:

downloadItem.setSavePath(path)

  • path String - Set the save file path of the download item.

The API is only available in session's will-download callback function. If user doesn't set the save path via the API, Electron will use the original routine to determine the save path(Usually prompts a save dialog).

downloadItem.getSavePath()

Returns String - The save path of the download item. This will be either the path set via downloadItem.setSavePath(path) or the path selected from the shown save dialog.

downloadItem.pause()

Pauses the download.

downloadItem.isPaused()

Returns Boolean - Whether the download is paused.

downloadItem.resume()

Resumes the download that has been paused.

Note: To enable resumable downloads the server you are downloading from must support range requests and provide both Last-Modified and ETag header values. Otherwise resume() will dismiss previously received bytes and restart the download from the beginning.

downloadItem.canResume()

Returns Boolean - Whether the download can resume.

downloadItem.cancel()

Cancels the download operation.

downloadItem.getURL()

Returns String - The origin url where the item is downloaded from.

downloadItem.getMimeType()

Returns String - The files mime type.

downloadItem.hasUserGesture()

Returns Boolean - Whether the download has user gesture.

downloadItem.getFilename()

Returns String - The file name of the download item.

Note: The file name is not always the same as the actual one saved in local disk. If user changes the file name in a prompted download saving dialog, the actual name of saved file will be different.

downloadItem.getTotalBytes()

Returns Integer - The total size in bytes of the download item.

If the size is unknown, it returns 0.

downloadItem.getReceivedBytes()

Returns Integer - The received bytes of the download item.

downloadItem.getContentDisposition()

Returns String - The Content-Disposition field from the response header.

downloadItem.getState()

Returns String - The current state. Can be progressing, completed, cancelled or interrupted.

Note: The following methods are useful specifically to resume a cancelled item when session is restarted.

downloadItem.getURLChain()

Returns String[] - The complete url chain of the item including any redirects.

downloadItem.getLastModifiedTime()

Returns String - Last-Modified header value.

downloadItem.getETag()

Returns String - ETag header value.

downloadItem.getStartTime()

Returns Double - Number of seconds since the UNIX epoch when the download was started.


Electron Versioning

A detailed look at our versioning policy and implementation.

As of version 2.0.0, Electron follows semver. The following command will install the most recent stable build of Electron:

npm install --save-dev electron

To update an existing project to use the latest stable version:

npm install --save-dev electron@latest

Version 1.x

Electron versions < 2.0 did not conform to the semver spec: major versions corresponded to end-user API changes, minor versions corresponded to Chromium major releases, and patch versions corresponded to new features and bug fixes. While convenient for developers merging features, it creates problems for developers of client-facing applications. The QA testing cycles of major apps like Slack, Stride, Teams, Skype, VS Code, Atom, and Desktop can be lengthy and stability is a highly desired outcome. There is a high risk in adopting new features while trying to absorb bug fixes.

Here is an example of the 1.x strategy:

An app developed with 1.8.1 cannot take the 1.8.3 bug fix without either absorbing the 1.8.2 feature, or by backporting the fix and maintaining a new release line.

Version 2.0 and Beyond

There are several major changes from our 1.x strategy outlined below. Each change is intended to satisfy the needs and priorities of developers/maintainers and app developers.

  1. Strict use of semver
  2. Introduction of semver-compliant -beta tags
  3. Introduction of conventional commit messages
  4. Well-defined stabilization branches
  5. The master branch is versionless; only stabilization branches contain version information

We will cover in detail how git branching works, how npm tagging works, what developers should expect to see, and how one can backport changes.

semver

From 2.0 onward, Electron will follow semver.

Below is a table explicitly mapping types of changes to their corresponding category of semver (e.g. Major, Minor, Patch).

Major Version Increments Minor Version Increments Patch Version Increments
Electron breaking API changes Electron non-breaking API changes Electron bug fixes
Node.js major version updates Node.js minor version updates Node.js patch version updates
Chromium version updates fix-related chromium patches

Note that most Chromium updates will be considered breaking. Fixes that can be backported will likely be cherry-picked as patches.

Stabilization Branches

Stabilization branches are branches that run parallel to master, taking in only cherry-picked commits that are related to security or stability. These branches are never merged back to master.

Stabilization branches are always either major or minor version lines, and named against the following template $MAJOR-$MINOR-x e.g. 2-0-x.

We allow for multiple stabilization branches to exist simultaneously, and intend to support at least two in parallel at all times, backporting security fixes as necessary.

Older lines will not be supported by GitHub, but other groups can take ownership and backport stability and security fixes on their own. We discourage this, but recognize that it makes life easier for many app developers.

Beta Releases and Bug Fixes

Developers want to know which releases are safe to use. Even seemingly innocent features can introduce regressions in complex applications. At the same time, locking to a fixed version is dangerous because you’re ignoring security patches and bug fixes that may have come out since your version. Our goal is to allow the following standard semver ranges in package.json :

  • Use ~2.0.0 to admit only stability or security related fixes to your 2.0.0 release.
  • Use ^2.0.0 to admit non-breaking reasonably stable feature work as well as security and bug fixes.

What’s important about the second point is that apps using ^ should still be able to expect a reasonable level of stability. To accomplish this, semver allows for a pre-release identifier to indicate a particular version is not yet safe or stable.

Whatever you choose, you will periodically have to bump the version in your package.json as breaking changes are a fact of Chromium life.

The process is as follows:

  1. All new major and minor releases lines begin with a beta series indicated by semver prerelease tags of beta.N, e.g. 2.0.0-beta.1. After the first beta, subsequent beta releases must meet all of the following conditions:

    1. The change is backwards API-compatible (deprecations are allowed)
    2. The risk to meeting our stability timeline must be low.
  2. If allowed changes need to be made once a release is beta, they are applied and the prerelease tag is incremented, e.g. 2.0.0-beta.2.
  3. If a particular beta release is generally regarded as stable, it will be re-released as a stable build, changing only the version information. e.g. 2.0.0. After the first stable, all changes must be backwards-compatible bug or security fixes.
  4. If future bug fixes or security patches need to be made once a release is stable, they are applied and the patch version is incremented e.g. 2.0.1.

Specifically, the above means:

  1. Admitting non-breaking-API changes early in the beta cycle is okay, even if those changes have the potential to cause moderate side-affects
  2. Admitting feature-flagged changes, that do not otherwise alter existing code paths, at most points in the beta cycle is okay. Users can explicitly enable those flags in their apps.
  3. Admitting features of any sort very late in the beta cycle is 👎 without a very good reason.

For each major and minor bump, you should expect to see something like the following:

2.0.0-beta.1
2.0.0-beta.2
2.0.0-beta.3
2.0.0
2.0.1
2.0.2

An example lifecycle in pictures:

  • A new release branch is created that includes the latest set of features. It is published as 2.0.0-beta.1.
  • A bug fix comes into master that can be backported to the release branch. The patch is applied, and a new beta is published as 2.0.0-beta.2.
  • The beta is considered generally stable and it is published again as a non-beta under 2.0.0.
  • Later, a zero-day exploit is revealed and a fix is applied to master. We backport the fix to the 2-0-x line and release 2.0.1.

A few examples of how various semver ranges will pick up new releases:

Missing Features: Alphas

Our strategy has a few tradeoffs, which for now we feel are appropriate. Most importantly that new features in master may take a while before reaching a stable release line. If you want to try a new feature immediately, you will have to build Electron yourself.

As a future consideration, we may introduce one or both of the following:

  • alpha releases that have looser stability constraints to betas; for example it would be allowable to admit new features while a stability channel is in alpha

Feature Flags

Feature flags are a common practice in Chromium, and are well-established in the web-development ecosystem. In the context of Electron, a feature flag or soft branch must have the following properties:

  • it is enabled/disabled either at runtime, or build-time; we do not support the concept of a request-scoped feature flag
  • it completely segments new and old code paths; refactoring old code to support a new feature violates the feature-flag contract
  • feature flags are eventually removed after the feature is released

Semantic Commits

We seek to increase clarity at all levels of the update and releases process. Starting with 2.0.0 we will require pull requests adhere to the Conventional Commits spec, which can be summarized as follows:

  • Commits that would result in a semver major bump must start their body with BREAKING CHANGE:.

  • Commits that would result in a semver minor bump must start with feat:.

  • Commits that would result in a semver patch bump must start with fix:.

  • We allow squashing of commits, provided that the squashed message adheres the the above message format.

  • It is acceptable for some commits in a pull request to not include a semantic prefix, as long as the pull request title contains a meaningful encompassing semantic message.

Versioned master

  • The master branch will always contain the next major version X.0.0-nightly.DATE in its package.json
  • Release branches are never merged back to master
  • Release branches do contain the correct version in their package.json
  • As soon as a release branch is cut for a major, master must be bumped to the next major. I.e. master is always versioned as the next theoretical release branch

Environment Variables

Control application configuration and behavior without changing code.

Certain Electron behaviors are controlled by environment variables because they are initialized earlier than the command line flags and the app's code.

POSIX shell example:

$ export ELECTRON_ENABLE_LOGGING=true
$ electron

Windows console example:

> set ELECTRON_ENABLE_LOGGING=true
> electron

Production Variables

The following environment variables are intended primarily for use at runtime in packaged Electron applications.

GOOGLE_API_KEY

Electron includes a hardcoded API key for making requests to Google's geocoding webservice. Because this API key is included in every version of Electron, it often exceeds its usage quota. To work around this, you can supply your own Google API key in the environment. Place the following code in your main process file, before opening any browser windows that will make geocoding requests:

process.env.GOOGLE_API_KEY = 'YOUR_KEY_HERE'

For instructions on how to acquire a Google API key, visit this page.

By default, a newly generated Google API key may not be allowed to make geocoding requests. To enable geocoding requests, visit this page.

ELECTRON_NO_ASAR

Disables ASAR support. This variable is only supported in forked child processes and spawned child processes that set ELECTRON_RUN_AS_NODE.

ELECTRON_RUN_AS_NODE

Starts the process as a normal Node.js process.

ELECTRON_NO_ATTACH_CONSOLE Windows

Don't attach to the current console session.

ELECTRON_FORCE_WINDOW_MENU_BAR Linux

Don't use the global menu bar on Linux.

ELECTRON_TRASH Linux

Set the trash implementation on Linux. Default is gio.

Options:

  • gvfs-trash
  • trash-cli
  • kioclient5
  • kioclient

Development Variables

The following environment variables are intended primarily for development and debugging purposes.

ELECTRON_ENABLE_LOGGING

Prints Chrome's internal logging to the console.

ELECTRON_LOG_ASAR_READS

When Electron reads from an ASAR file, log the read offset and file path to the system tmpdir. The resulting file can be provided to the ASAR module to optimize file ordering.

ELECTRON_ENABLE_STACK_DUMPING

Prints the stack trace to the console when Electron crashes.

This environment variable will not work if the crashReporter is started.

ELECTRON_DEFAULT_ERROR_MODE Windows

Shows the Windows's crash dialog when Electron crashes.

This environment variable will not work if the crashReporter is started.

ELECTRON_OVERRIDE_DIST_PATH

When running from the electron package, this variable tells the electron command to use the specified build of Electron instead of the one downloaded by npm install. Usage:

export ELECTRON_OVERRIDE_DIST_PATH=/Users/username/projects/electron/out/D

Why am I having trouble installing Electron?

When running npm install electron, some users occasionally encounter installation errors.

In almost all cases, these errors are the result of network problems and not actual issues with the electron npm package. Errors like ELIFECYCLE, EAI_AGAIN, ECONNRESET, and ETIMEDOUT are all indications of such network problems. The best resolution is to try switching networks, or wait a bit and try installing again.

You can also attempt to download Electron directly from electron/electron/releases if installing via npm is failing.

When will Electron upgrade to latest Chrome?

The Chrome version of Electron is usually bumped within one or two weeks after a new stable Chrome version gets released. This estimate is not guaranteed and depends on the amount of work involved with upgrading.

Only the stable channel of Chrome is used. If an important fix is in beta or dev channel, we will back-port it.

For more information, please see the security introduction.

When will Electron upgrade to latest Node.js?

When a new version of Node.js gets released, we usually wait for about a month before upgrading the one in Electron. So we can avoid getting affected by bugs introduced in new Node.js versions, which happens very often.

New features of Node.js are usually brought by V8 upgrades, since Electron is using the V8 shipped by Chrome browser, the shiny new JavaScript feature of a new Node.js version is usually already in Electron.

How to share data between web pages?

To share data between web pages (the renderer processes) the simplest way is to use HTML5 APIs which are already available in browsers. Good candidates are Storage API, localStorage, sessionStorage, and IndexedDB.

Or you can use the IPC system, which is specific to Electron, to store objects in the main process as a global variable, and then to access them from the renderers through the remote property of electron module:

// In the main process.
global.sharedObject = {
  someProperty: 'default value'
}
// In page 1.
require('electron').remote.getGlobal('sharedObject').someProperty = 'new value'
// In page 2.
console.log(require('electron').remote.getGlobal('sharedObject').someProperty)

My app's window/tray disappeared after a few minutes.

This happens when the variable which is used to store the window/tray gets garbage collected.

If you encounter this problem, the following articles may prove helpful:

If you want a quick fix, you can make the variables global by changing your code from this:

const { app, Tray } = require('electron')
app.on('ready', () => {
  const tray = new Tray('/path/to/icon.png')
  tray.setTitle('hello world')
})

to this:

const { app, Tray } = require('electron')
let tray = null
app.on('ready', () => {
  tray = new Tray('/path/to/icon.png')
  tray.setTitle('hello world')
})

I can not use jQuery/RequireJS/Meteor/AngularJS in Electron.

Due to the Node.js integration of Electron, there are some extra symbols inserted into the DOM like module, exports, require. This causes problems for some libraries since they want to insert the symbols with the same names.

To solve this, you can turn off node integration in Electron:

// In the main process.
const { BrowserWindow } = require('electron')
let win = new BrowserWindow({
  webPreferences: {
    nodeIntegration: false
  }
})
win.show()

But if you want to keep the abilities of using Node.js and Electron APIs, you have to rename the symbols in the page before including other libraries:

<head>
<script>
window.nodeRequire = require;
delete window.require;
delete window.exports;
delete window.module;
</script>
<script type="text/javascript" src="jquery.js"></script>
</head>

require('electron').xxx is undefined.

When using Electron's built-in module you might encounter an error like this:

> require('electron').webFrame.setZoomFactor(1.0)
Uncaught TypeError: Cannot read property 'setZoomLevel' of undefined

This is because you have the npm electron module installed either locally or globally, which overrides Electron's built-in module.

To verify whether you are using the correct built-in module, you can print the path of the electron module:

console.log(require.resolve('electron'))

and then check if it is in the following form:

"/path/to/Electron.app/Contents/Resources/atom.asar/renderer/api/lib/exports/electron.js"

If it is something like node_modules/electron/index.js, then you have to either remove the npm electron module, or rename it.

npm uninstall electron
npm uninstall -g electron

However if you are using the built-in module but still getting this error, it is very likely you are using the module in the wrong process. For example electron.app can only be used in the main process, while electron.webFrame is only available in renderer processes.


FileFilter Object

  • name String
  • extensions String[]

File Object

Use the HTML5 File API to work natively with files on the filesystem.

The DOM's File interface provides abstraction around native files in order to let users work on native files directly with the HTML5 file API. Electron has added a path attribute to the File interface which exposes the file's real path on filesystem.

Example of getting a real path from a dragged-onto-the-app file:

<div id="holder">
  Drag your file here
</div>

<script>
  document.addEventListener('drop', function (e) {
    e.preventDefault();
    e.stopPropagation();
    
    for (let f of e.dataTransfer.files) {
      console.log('File(s) you dragged here: ', f.path)
    }
  });
  document.addEventListener('dragover', function (e) {
    e.preventDefault();
    e.stopPropagation();
  });
</script>

Writing Your First Electron App

Electron enables you to create desktop applications with pure JavaScript by providing a runtime with rich native (operating system) APIs. You could see it as a variant of the Node.js runtime that is focused on desktop applications instead of web servers.

This doesn't mean Electron is a JavaScript binding to graphical user interface (GUI) libraries. Instead, Electron uses web pages as its GUI, so you could also see it as a minimal Chromium browser, controlled by JavaScript.

Note: This example is also available as a repository you can download and run immediately.

As far as development is concerned, an Electron application is essentially a Node.js application. The starting point is a package.json that is identical to that of a Node.js module. A most basic Electron app would have the following folder structure:

your-app/
├── package.json
├── main.js
└── index.html

Create a new empty folder for your new Electron application. Open up your command line client and run npm init from that very folder.

npm init

npm will guide you through creating a basic package.json file. The script specified by the main field is the startup script of your app, which will run the main process. An example of your package.json might look like this:

{
  "name": "your-app",
  "version": "0.1.0",
  "main": "main.js"
}

Note: If the main field is not present in package.json, Electron will attempt to load an index.js (as Node.js does). If this was actually a simple Node application, you would add a start script that instructs node to execute the current package:

{
  "name": "your-app",
  "version": "0.1.0",
  "main": "main.js",
  "scripts": {
    "start": "node ."
  }
}

Turning this Node application into an Electron application is quite simple - we merely replace the node runtime with the electron runtime.

{
  "name": "your-app",
  "version": "0.1.0",
  "main": "main.js",
  "scripts": {
    "start": "electron ."
  }
}

Installing Electron

At this point, you'll need to install electron itself. The recommended way of doing so is to install it as a development dependency in your app, which allows you to work on multiple apps with different Electron versions. To do so, run the following command from your app's directory:

npm install --save-dev electron

Other means for installing Electron exist. Please consult the installation guide to learn about use with proxies, mirrors, and custom caches.

Electron Development in a Nutshell

Electron apps are developed in JavaScript using the same principles and methods found in Node.js development. All APIs and features found in Electron are accessible through the electron module, which can be required like any other Node.js module:

const electron = require('electron')

The electron module exposes features in namespaces. As examples, the lifecycle of the application is managed through electron.app, windows can be created using the electron.BrowserWindow class. A simple main.js file might wait for the application to be ready and open a window:

const { app, BrowserWindow } = require('electron')

function createWindow () {
  // Create the browser window.
  win = new BrowserWindow({ width: 800, height: 600 })

  // and load the index.html of the app.
  win.loadFile('index.html')
}

app.on('ready', createWindow)

The main.js should create windows and handle all the system events your application might encounter. A more complete version of the above example might open developer tools, handle the window being closed, or re-create windows on macOS if the user clicks on the app's icon in the dock.

const { app, BrowserWindow } = require('electron')

// Keep a global reference of the window object, if you don't, the window will
// be closed automatically when the JavaScript object is garbage collected.
let win

function createWindow () {
  // Create the browser window.
  win = new BrowserWindow({ width: 800, height: 600 })

  // and load the index.html of the app.
  win.loadFile('index.html')

  // Open the DevTools.
  win.webContents.openDevTools()

  // Emitted when the window is closed.
  win.on('closed', () => {
    // Dereference the window object, usually you would store windows
    // in an array if your app supports multi windows, this is the time
    // when you should delete the corresponding element.
    win = null
  })
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.on('ready', createWindow)

// Quit when all windows are closed.
app.on('window-all-closed', () => {
  // On macOS it is common for applications and their menu bar
  // to stay active until the user quits explicitly with Cmd + Q
  if (process.platform !== 'darwin') {
    app.quit()
  }
})

app.on('activate', () => {
  // On macOS it's common to re-create a window in the app when the
  // dock icon is clicked and there are no other windows open.
  if (win === null) {
    createWindow()
  }
})

// In this file you can include the rest of your app's specific main process
// code. You can also put them in separate files and require them here.

Finally the index.html is the web page you want to show:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Hello World!</title>
  </head>
  <body>
    <h1>Hello World!</h1>
    We are using node <script>document.write(process.versions.node)</script>,
    Chrome <script>document.write(process.versions.chrome)</script>,
    and Electron <script>document.write(process.versions.electron)</script>.
  </body>
</html>

Running Your App

Once you've created your initial main.js, index.html, and package.json files, you can try your app by running npm start from your application's directory.

Trying this Example

Clone and run the code in this tutorial by using the electron/electron-quick-start repository.

Note: Running this requires Git and npm.

# Clone the repository
$ git clone https://github.com/electron/electron-quick-start
# Go into the repository
$ cd electron-quick-start
# Install dependencies
$ npm install
# Run the app
$ npm start

For a list of boilerplates and tools to kick-start your development process, see the Boilerplates and CLIs documentation.


Frameless Window

Open a window without toolbars, borders, or other graphical "chrome".

A frameless window is a window that has no chrome, the parts of the window, like toolbars, that are not a part of the web page. These are options on the BrowserWindow class.

Create a frameless window

To create a frameless window, you need to set frame to false in BrowserWindow's options:

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({width: 800, height: 600, frame: false})
win.show()

Alternatives on macOS

On macOS 10.9 Mavericks and newer, there's an alternative way to specify a chromeless window. Instead of setting frame to false which disables both the titlebar and window controls, you may want to have the title bar hidden and your content extend to the full window size, yet still preserve the window controls ("traffic lights") for standard window actions. You can do so by specifying the titleBarStyle option:

hidden

Results in a hidden title bar and a full size content window, yet the title bar still has the standard window controls (“traffic lights”) in the top left.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({titleBarStyle: 'hidden'})
win.show()

hiddenInset

Results in a hidden title bar with an alternative look where the traffic light buttons are slightly more inset from the window edge.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({titleBarStyle: 'hiddenInset'})
win.show()

customButtonsOnHover

Uses custom drawn close, miniaturize, and fullscreen buttons that display when hovering in the top left of the window. These custom buttons prevent issues with mouse events that occur with the standard window toolbar buttons. This option is only applicable for frameless windows.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({titleBarStyle: 'customButtonsOnHover', frame: false})
win.show()

Transparent window

By setting the transparent option to true, you can also make the frameless window transparent:

const {BrowserWindow} = require('electron')
let win = new BrowserWindow({transparent: true, frame: false})
win.show()

Limitations

  • You can not click through the transparent area. We are going to introduce an API to set window shape to solve this, see our issue for details.
  • Transparent windows are not resizable. Setting resizable to true may make a transparent window stop working on some platforms.
  • The blur filter only applies to the web page, so there is no way to apply blur effect to the content below the window (i.e. other applications open on the user's system).
  • On Windows operating systems, transparent windows will not work when DWM is disabled.
  • On Linux, users have to put --enable-transparent-visuals --disable-gpu in the command line to disable GPU and allow ARGB to make transparent window, this is caused by an upstream bug that alpha channel doesn't work on some NVidia drivers on Linux.
  • On Mac, the native window shadow will not be shown on a transparent window.

Click-through window

To create a click-through window, i.e. making the window ignore all mouse events, you can call the win.setIgnoreMouseEvents(ignore) API:

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()
win.setIgnoreMouseEvents(true)

Forwarding

Ignoring mouse messages makes the web page oblivious to mouse movement, meaning that mouse movement events will not be emitted. On Windows operating systems an optional parameter can be used to forward mouse move messages to the web page, allowing events such as mouseleave to be emitted:

let win = require('electron').remote.getCurrentWindow()
let el = document.getElementById('clickThroughElement')
el.addEventListener('mouseenter', () => {
  win.setIgnoreMouseEvents(true, {forward: true})
})
el.addEventListener('mouseleave', () => {
  win.setIgnoreMouseEvents(false)
})

This makes the web page click-through when over el, and returns to normal outside it.

Draggable region

By default, the frameless window is non-draggable. Apps need to specify -webkit-app-region: drag in CSS to tell Electron which regions are draggable (like the OS's standard titlebar), and apps can also use -webkit-app-region: no-drag to exclude the non-draggable area from the draggable region. Note that only rectangular shapes are currently supported.

Note: -webkit-app-region: drag is known to have problems while the developer tools are open. See this GitHub issue for more information including a workaround.

To make the whole window draggable, you can add -webkit-app-region: drag as body's style:

<body style="-webkit-app-region: drag">
</body>

And note that if you have made the whole window draggable, you must also mark buttons as non-draggable, otherwise it would be impossible for users to click on them:

button {
  -webkit-app-region: no-drag;
}

If you're only setting a custom titlebar as draggable, you also need to make all buttons in titlebar non-draggable.

Text selection

In a frameless window the dragging behaviour may conflict with selecting text. For example, when you drag the titlebar you may accidentally select the text on the titlebar. To prevent this, you need to disable text selection within a draggable area like this:

.titlebar {
  -webkit-user-select: none;
  -webkit-app-region: drag;
}

Context menu

On some platforms, the draggable area will be treated as a non-client frame, so when you right click on it a system menu will pop up. To make the context menu behave correctly on all platforms you should never use a custom context menu on draggable areas.


globalShortcut

Detect keyboard events when the application does not have keyboard focus.

Process: Main

The globalShortcut module can register/unregister a global keyboard shortcut with the operating system so that you can customize the operations for various shortcuts.

Note: The shortcut is global; it will work even if the app does not have the keyboard focus. You should not use this module until the ready event of the app module is emitted.

const {app, globalShortcut} = require('electron')

app.on('ready', () => {
  // Register a 'CommandOrControl+X' shortcut listener.
  const ret = globalShortcut.register('CommandOrControl+X', () => {
    console.log('CommandOrControl+X is pressed')
  })

  if (!ret) {
    console.log('registration failed')
  }

  // Check whether a shortcut is registered.
  console.log(globalShortcut.isRegistered('CommandOrControl+X'))
})

app.on('will-quit', () => {
  // Unregister a shortcut.
  globalShortcut.unregister('CommandOrControl+X')

  // Unregister all shortcuts.
  globalShortcut.unregisterAll()
})

Methods

The globalShortcut module has the following methods:

globalShortcut.register(accelerator, callback)

Registers a global shortcut of accelerator. The callback is called when the registered shortcut is pressed by the user.

When the accelerator is already taken by other applications, this call will silently fail. This behavior is intended by operating systems, since they don't want applications to fight for global shortcuts.

globalShortcut.isRegistered(accelerator)

Returns Boolean - Whether this application has registered accelerator.

When the accelerator is already taken by other applications, this call will still return false. This behavior is intended by operating systems, since they don't want applications to fight for global shortcuts.

globalShortcut.unregister(accelerator)

Unregisters the global shortcut of accelerator.

globalShortcut.unregisterAll()

Unregisters all of the global shortcuts.


Glossary

This page defines some terminology that is commonly used in Electron development.

ASAR

ASAR stands for Atom Shell Archive Format. An asar archive is a simple tar-like format that concatenates files into a single file. Electron can read arbitrary files from it without unpacking the whole file.

The ASAR format was created primarily to improve performance on Windows... TODO

CRT

The C Run-time Library (CRT) is the part of the C++ Standard Library that incorporates the ISO C99 standard library. The Visual C++ libraries that implement the CRT support native code development, and both mixed native and managed code, and pure managed code for .NET development.

DMG

An Apple Disk Image is a packaging format used by macOS. DMG files are commonly used for distributing application "installers". electron-builder supports dmg as a build target.

IME

Input Method Editor. A program that allows users to enter characters and symbols not found on their keyboard. For example, this allows users of Latin keyboards to input Chinese, Japanese, Korean and Indic characters.

IDL

Interface description language. Write function signatures and data types in a format that can be used to generate interfaces in Java, C++, JavaScript, etc.

IPC

IPC stands for Inter-Process Communication. Electron uses IPC to send serialized JSON messages between the main and renderer processes.

libchromiumcontent

A shared library that includes the Chromium Content module and all its dependencies (e.g., Blink, V8, etc.). Also referred to as "libcc".

main process

The main process, commonly a file named main.js, is the entry point to every Electron app. It controls the life of the app, from open to close. It also manages native elements such as the Menu, Menu Bar, Dock, Tray, etc. The main process is responsible for creating each new renderer process in the app. The full Node API is built in.

Every app's main process file is specified in the main property in package.json. This is how electron . knows what file to execute at startup.

In Chromium, this process is referred to as the "browser process". It is renamed in Electron to avoid confusion with renderer processes.

See also: process, renderer process

MAS

Acronym for Apple's Mac App Store. For details on submitting your app to the MAS, see the Mac App Store Submission Guide.

Mojo

An IPC system for communicating intra- or inter-process, and that's important because Chrome is keen on being able to split its work into separate processes or not, depending on memory pressures etc.

See https://chromium.googlesource.com/chromium/src/+/master/mojo/README.md

native modules

Native modules (also called addons in Node.js) are modules written in C or C++ that can be loaded into Node.js or Electron using the require() function, and used as if they were an ordinary Node.js module. They are used primarily to provide an interface between JavaScript running in Node.js and C/C++ libraries.

Native Node modules are supported by Electron, but since Electron is very likely to use a different V8 version from the Node binary installed in your system, you have to manually specify the location of Electron’s headers when building native modules.

See also Using Native Node Modules.

NSIS

Nullsoft Scriptable Install System is a script-driven Installer authoring tool for Microsoft Windows. It is released under a combination of free software licenses, and is a widely-used alternative to commercial proprietary products like InstallShield. electron-builder supports NSIS as a build target.

OSR

OSR (Off-screen rendering) can be used for loading heavy page in background and then displaying it after (it will be much faster). It allows you to render page without showing it on screen.

process

A process is an instance of a computer program that is being executed. Electron apps that make use of the main and one or many renderer process are actually running several programs simultaneously.

In Node.js and Electron, each running process has a process object. This object is a global that provides information about, and control over, the current process. As a global, it is always available to applications without using require().

See also: main process, renderer process

renderer process

The renderer process is a browser window in your app. Unlike the main process, there can be multiple of these and each is run in a separate process. They can also be hidden.

In normal browsers, web pages usually run in a sandboxed environment and are not allowed access to native resources. Electron users, however, have the power to use Node.js APIs in web pages allowing lower level operating system interactions.

See also: process, main process

Squirrel

Squirrel is an open-source framework that enables Electron apps to update automatically as new versions are released. See the autoUpdater API for info about getting started with Squirrel.

userland

This term originated in the Unix community, where "userland" or "userspace" referred to programs that run outside of the operating system kernel. More recently, the term has been popularized in the Node and npm community to distinguish between the features available in "Node core" versus packages published to the npm registry by the much larger "user" community.

Like Node, Electron is focused on having a small set of APIs that provide all the necessary primitives for developing multi-platform desktop applications. This design philosophy allows Electron to remain a flexible tool without being overly prescriptive about how it should be used. Userland enables users to create and share tools that provide additional functionality on top of what is available in "core".

V8

V8 is Google's open source JavaScript engine. It is written in C++ and is used in Google Chrome. V8 can run standalone, or can be embedded into any C++ application.

Electron builds V8 as part of Chromium and then points Node to that V8 when building it.

V8's version numbers always correspond to those of Google Chrome. Chrome 59 includes V8 5.9, Chrome 58 includes V8 5.8, etc.

webview

webview tags are used to embed 'guest' content (such as external web pages) in your Electron app. They are similar to iframes, but differ in that each webview runs in a separate process. It doesn't have the same permissions as your web page and all interactions between your app and embedded content will be asynchronous. This keeps your app safe from the embedded content.


GPUFeatureStatus Object

  • 2d_canvas String - Canvas
  • flash_3d String - Flash
  • flash_stage3d String - Flash Stage3D
  • flash_stage3d_baseline String - Flash Stage3D Baseline profile
  • gpu_compositing String - Compositing
  • multiple_raster_threads String - Multiple Raster Threads
  • native_gpu_memory_buffers String - Native GpuMemoryBuffers
  • rasterization String - Rasterization
  • video_decode String - Video Decode
  • video_encode String - Video Encode
  • vpx_decode String - VPx Video Decode
  • webgl String - WebGL
  • webgl2 String - WebGL2

Possible values:

  • disabled_software - Software only. Hardware acceleration disabled (yellow)
  • disabled_off - Disabled (red)
  • disabled_off_ok - Disabled (yellow)
  • unavailable_software - Software only, hardware acceleration unavailable (yellow)
  • unavailable_off - Unavailable (red)
  • unavailable_off_ok - Unavailable (yellow)
  • enabled_readback - Hardware accelerated but at reduced performance (yellow)
  • enabled_force - Hardware accelerated on all pages (green)
  • enabled - Hardware accelerated (green)
  • enabled_on - Enabled (green)
  • enabled_force_on - Force enabled (green)

inAppPurchase

In-app purchases on Mac App Store.

Process: Main

Events

The inAppPurchase module emits the following events:

Event: 'transactions-updated'

Emitted when one or more transactions have been updated.

Returns:

  • event Event
  • transactions Transaction[] - Array of Transaction objects.

Methods

The inAppPurchase module has the following methods:

inAppPurchase.purchaseProduct(productID, quantity, callback)

  • productID String - The identifiers of the product to purchase. (The identifier of com.example.app.product1 is product1).
  • quantity Integer (optional) - The number of items the user wants to purchase.
  • callback Function (optional) - The callback called when the payment is added to the PaymentQueue.

    • isProductValid Boolean - Determine if the product is valid and added to the payment queue.

You should listen for the transactions-updated event as soon as possible and certainly before you call purchaseProduct.

inAppPurchase.getProducts(productIDs, callback)

  • productIDs String[] - The identifiers of the products to get.
  • callback Function - The callback called with the products or an empty array if the products don't exist.

    • products Product[] - Array of Product objects

Retrieves the product descriptions.

inAppPurchase.canMakePayments()

Returns Boolean, whether a user can make a payment.

inAppPurchase.getReceiptURL()

Returns String, the path to the receipt.

inAppPurchase.finishAllTransactions()

Completes all pending transactions.

inAppPurchase.finishTransactionByDate(date)

  • date String - The ISO formatted date of the transaction to finish.

Completes the pending transactions corresponding to the date.


If you haven't already, you’ll need to sign the Paid Applications Agreement and set up your banking and tax information in iTunes Connect.

iTunes Connect Developer Help: Agreements, tax, and banking overview

Create Your In-App Purchases

Then, you'll need to configure your in-app purchases in iTunes Connect, and include details such as name, pricing, and description that highlights the features and functionality of your in-app purchase.

iTunes Connect Developer Help: Create an in-app purchase

Change the CFBundleIdentifier

To test In-App Purchase in development with Electron you'll have to change the CFBundleIdentifier in node_modules/electron/dist/Electron.app/Contents/Info.plist. You have to replace com.github.electron by the bundle identifier of the application you created with iTunes Connect.

<key>CFBundleIdentifier</key>
<string>com.example.app</string>

Code example

Here is an example that shows how to use In-App Purchases in Electron. You'll have to replace the product ids by the identifiers of the products created with iTunes Connect (the identifier of com.example.app.product1 is product1). Note that you have to listen to the transactions-updated event as soon as possible in your app.

const { inAppPurchase } = require('electron').remote
const PRODUCT_IDS = ['id1', 'id2']

// Listen for transactions as soon as possible.
inAppPurchase.on('transactions-updated', (event, transactions) => {
  if (!Array.isArray(transactions)) {
    return
  }

  // Check each transaction.
  transactions.forEach(function (transaction) {
    var payment = transaction.payment

    switch (transaction.transactionState) {
      case 'purchasing':
        console.log(`Purchasing ${payment.productIdentifier}...`)
        break
      case 'purchased':

        console.log(`${payment.productIdentifier} purchased.`)

        // Get the receipt url.
        let receiptURL = inAppPurchase.getReceiptURL()

        console.log(`Receipt URL: ${receiptURL}`)

        // Submit the receipt file to the server and check if it is valid.
        // @see https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html
        // ...
        // If the receipt is valid, the product is purchased
        // ...

        // Finish the transaction.
        inAppPurchase.finishTransactionByDate(transaction.transactionDate)

        break
      case 'failed':

        console.log(`Failed to purchase ${payment.productIdentifier}.`)

        // Finish the transaction.
        inAppPurchase.finishTransactionByDate(transaction.transactionDate)

        break
      case 'restored':

        console.log(`The purchase of ${payment.productIdentifier} has been restored.`)

        break
      case 'deferred':

        console.log(`The purchase of ${payment.productIdentifier} has been deferred.`)

        break
      default:
        break
    }
  })
})

// Check if the user is allowed to make in-app purchase.
if (!inAppPurchase.canMakePayments()) {
  console.log('The user is not allowed to make in-app purchase.')
}

// Retrieve and display the product descriptions.
inAppPurchase.getProducts(PRODUCT_IDS, (products) => {
  // Check the parameters.
  if (!Array.isArray(products) || products.length <= 0) {
    console.log('Unable to retrieve the product informations.')
    return
  }

  // Display the name and price of each product.
  products.forEach((product) => {
    console.log(`The price of ${product.localizedTitle} is ${product.formattedPrice}.`)
  })

  // Ask the user which product he/she wants to purchase.
  // ...
  let selectedProduct = products[0]
  let selectedQuantity = 1

  // Purchase the selected product.
  inAppPurchase.purchaseProduct(selectedProduct.productIdentifier, selectedQuantity, (isProductValid) => {
    if (!isProductValid) {
      console.log('The product is not valid.')
      return
    }

    console.log('The payment has been added to the payment queue.')
  })
})

Class: IncomingMessage

Handle responses to HTTP/HTTPS requests.

Process: Main

IncomingMessage implements the Readable Stream interface and is therefore an EventEmitter.

Event: 'data'

Returns:

  • chunk Buffer - A chunk of response body's data.

The data event is the usual method of transferring response data into applicative code.

Event: 'end'

Indicates that response body has ended.

Event: 'aborted'

Emitted when a request has been canceled during an ongoing HTTP transaction.

Event: 'error'

Returns:

error Error - Typically holds an error string identifying failure root cause.

Emitted when an error was encountered while streaming response data events. For instance, if the server closes the underlying while the response is still streaming, an error event will be emitted on the response object and a close event will subsequently follow on the request object.

Instance Properties

An IncomingMessage instance has the following readable properties:

response.statusCode

An Integer indicating the HTTP response status code.

response.statusMessage

A String representing the HTTP status message.

response.headers

An Object representing the response HTTP headers. The headers object is formatted as follows:

  • All header names are lowercased.
  • Each header name produces an array-valued property on the headers object.
  • Each header value is pushed into the array associated with its header name.

response.httpVersion

A String indicating the HTTP protocol version number. Typical values are '1.0' or '1.1'. Additionally httpVersionMajor and httpVersionMinor are two Integer-valued readable properties that return respectively the HTTP major and minor version numbers.

response.httpVersionMajor

An Integer indicating the HTTP protocol major version number.

response.httpVersionMinor

An Integer indicating the HTTP protocol minor version number.


Installation

To install prebuilt Electron binaries, use npm. The preferred method is to install Electron as a development dependency in your app:

npm install electron --save-dev

See the Electron versioning doc for info on how to manage Electron versions in your apps.

Global Installation

You can also install the electron command globally in your $PATH:

npm install electron -g

Customization

If you want to change the architecture that is downloaded (e.g., ia32 on an x64 machine), you can use the --arch flag with npm install or set the npm_config_arch environment variable:

npm install --arch=ia32 electron

In addition to changing the architecture, you can also specify the platform (e.g., win32, linux, etc.) using the --platform flag:

npm install --platform=win32 electron

Proxies

If you need to use an HTTP proxy you can set these environment variables.

Custom Mirrors and Caches

During installation, the electron module will call out to electron-download to download prebuilt binaries of Electron for your platform. It will do so by contacting GitHub's release download page (https://github.com/electron/electron/releases/tag/v$VERSION, where $VERSION is the exact version of Electron).

If you are unable to access GitHub or you need to provide a custom build, you can do so by either providing a mirror or an existing cache directory.

Mirror

You can use environment variables to override the base URL, the path at which to look for Electron binaries, and the binary filename. The url used by electron-download is composed as follows:

url = ELECTRON_MIRROR + ELECTRON_CUSTOM_DIR + '/' + ELECTRON_CUSTOM_FILENAME

For instance, to use the China mirror:

ELECTRON_MIRROR="https://npm.taobao.org/mirrors/electron/"

Cache

Alternatively, you can override the local cache. electron-download will cache downloaded binaries in a local directory to not stress your network. You can use that cache folder to provide custom builds of Electron or to avoid making contact with the network at all.

  • Linux: $XDG_CACHE_HOME or ~/.cache/electron/
  • MacOS: ~/Library/Caches/electron/
  • Windows: $LOCALAPPDATA/electron/Cache or ~/AppData/Local/electron/Cache/

On environments that have been using older versions of Electron, you might find the cache also in ~/.electron.

You can also override the local cache location by providing a ELECTRON_CACHE environment variable.

The cache contains the version's official zip file as well as a checksum, stored as a text file. A typical cache might look like this:

├── electron-v1.7.9-darwin-x64.zip
├── electron-v1.8.1-darwin-x64.zip
├── electron-v1.8.2-beta.1-darwin-x64.zip
├── electron-v1.8.2-beta.2-darwin-x64.zip
├── electron-v1.8.2-beta.3-darwin-x64.zip
├── SHASUMS256.txt-1.7.9
├── SHASUMS256.txt-1.8.1
├── SHASUMS256.txt-1.8.2-beta.1
├── SHASUMS256.txt-1.8.2-beta.2
├── SHASUMS256.txt-1.8.2-beta.3

Troubleshooting

When running npm install electron, some users occasionally encounter installation errors.

In almost all cases, these errors are the result of network problems and not actual issues with the electron npm package. Errors like ELIFECYCLE, EAI_AGAIN, ECONNRESET, and ETIMEDOUT are all indications of such network problems. The best resolution is to try switching networks, or wait a bit and try installing again.

You can also attempt to download Electron directly from electron/electron/releases if installing via npm is failing.

If installation fails with an EACCESS error you may need to fix your npm permissions.

If the above error persists, the unsafe-perm flag may need to be set to true:

sudo npm install electron --unsafe-perm=true

On slower networks, it may be advisable to use the --verbose flag in order to show download progress:

npm install --verbose electron

If you need to force a re-download of the asset and the SHASUM file set the force_no_cache environment variable to true.


IOCounters Object

  • readOperationCount Number - The number of I/O read operations.
  • writeOperationCount Number - The number of I/O write operations.
  • otherOperationCount Number - Then number of I/O other operations.
  • readTransferCount Number - The number of I/O read transfers.
  • writeTransferCount Number - The number of I/O write transfers.
  • otherTransferCount Number - Then number of I/O other transfers.

ipcMain

Communicate asynchronously from the main process to renderer processes.

Process: Main

The ipcMain module is an instance of the EventEmitter class. When used in the main process, it handles asynchronous and synchronous messages sent from a renderer process (web page). Messages sent from a renderer will be emitted to this module.

Sending Messages

It is also possible to send messages from the main process to the renderer process, see webContents.send for more information.

  • When sending a message, the event name is the channel.
  • To reply to a synchronous message, you need to set event.returnValue.
  • To send an asynchronous message back to the sender, you can use event.sender.send(...).

An example of sending and handling messages between the render and main processes:

// In main process.
const {ipcMain} = require('electron')
ipcMain.on('asynchronous-message', (event, arg) => {
  console.log(arg) // prints "ping"
  event.sender.send('asynchronous-reply', 'pong')
})

ipcMain.on('synchronous-message', (event, arg) => {
  console.log(arg) // prints "ping"
  event.returnValue = 'pong'
})
// In renderer process (web page).
const {ipcRenderer} = require('electron')
console.log(ipcRenderer.sendSync('synchronous-message', 'ping')) // prints "pong"

ipcRenderer.on('asynchronous-reply', (event, arg) => {
  console.log(arg) // prints "pong"
})
ipcRenderer.send('asynchronous-message', 'ping')

Methods

The ipcMain module has the following method to listen for events:

ipcMain.on(channel, listener)

  • channel String
  • listener Function

Listens to channel, when a new message arrives listener would be called with listener(event, args...).

ipcMain.once(channel, listener)

  • channel String
  • listener Function

Adds a one time listener function for the event. This listener is invoked only the next time a message is sent to channel, after which it is removed.

ipcMain.removeListener(channel, listener)

  • channel String
  • listener Function

Removes the specified listener from the listener array for the specified channel.

ipcMain.removeAllListeners([channel])

  • channel String

Removes listeners of the specified channel.

Event object

The event object passed to the callback has the following methods:

event.returnValue

Set this to the value to be returned in a synchronous message.

event.sender

Returns the webContents that sent the message, you can call event.sender.send to reply to the asynchronous message, see webContents.send for more information.


ipcRenderer

Communicate asynchronously from a renderer process to the main process.

Process: Renderer

The ipcRenderer module is an instance of the EventEmitter class. It provides a few methods so you can send synchronous and asynchronous messages from the render process (web page) to the main process. You can also receive replies from the main process.

See ipcMain for code examples.

Methods

The ipcRenderer module has the following method to listen for events and send messages:

ipcRenderer.on(channel, listener)

  • channel String
  • listener Function

Listens to channel, when a new message arrives listener would be called with listener(event, args...).

ipcRenderer.once(channel, listener)

  • channel String
  • listener Function

Adds a one time listener function for the event. This listener is invoked only the next time a message is sent to channel, after which it is removed.

ipcRenderer.removeListener(channel, listener)

  • channel String
  • listener Function

Removes the specified listener from the listener array for the specified channel.

ipcRenderer.removeAllListeners(channel)

  • channel String

Removes all listeners, or those of the specified channel.

ipcRenderer.send(channel[, arg1][, arg2][, ...])

  • channel String
  • ...args any[]

Send a message to the main process asynchronously via channel, you can also send arbitrary arguments. Arguments will be serialized in JSON internally and hence no functions or prototype chain will be included.

The main process handles it by listening for channel with ipcMain module.

ipcRenderer.sendSync(channel[, arg1][, arg2][, ...])

  • channel String
  • ...args any[]

Returns any - The value sent back by the ipcMain handler.

Send a message to the main process synchronously via channel, you can also send arbitrary arguments. Arguments will be serialized in JSON internally and hence no functions or prototype chain will be included.

The main process handles it by listening for channel with ipcMain module, and replies by setting event.returnValue.

Note: Sending a synchronous message will block the whole renderer process, unless you know what you are doing you should never use it.

ipcRenderer.sendTo(webContentsId, channel, [, arg1][, arg2][, ...])

  • webContentsId Number
  • channel String
  • ...args any[]

Sends a message to a window with webContentsId via channel.

ipcRenderer.sendToHost(channel[, arg1][, arg2][, ...])

  • channel String
  • ...args any[]

Like ipcRenderer.send but the event will be sent to the <webview> element in the host page instead of the main process.


How to Contribute in Issues

For any issue, there are fundamentally three ways an individual can contribute:

  1. By opening the issue for discussion: If you believe that you have found a new bug in Electron, you should report it by creating a new issue in the electron/electron issue tracker.
  2. By helping to triage the issue: You can do this either by providing assistive details (a reproducible test case that demonstrates a bug) or by providing suggestions to address the issue.
  3. By helping to resolve the issue: This can be done by demonstrating that the issue is not a bug or is fixed; but more often, by opening a pull request that changes the source in electron/electron in a concrete and reviewable manner.

Asking for General Help

"Finding Support" has a list of resources for getting programming help, reporting security issues, contributing, and more. Please use the issue tracker for bugs only!

Submitting a Bug Report

When opening a new issue in the electron/electron issue tracker, users will be presented with a template that should be filled in.

<!--
Thanks for opening an issue! A few things to keep in mind:

- The issue tracker is only for bugs and feature requests.
- Before reporting a bug, please try reproducing your issue against
  the latest version of Electron.
- If you need general advice, join our Slack: http://atom-slack.herokuapp.com
-->

* Electron version:
* Operating system:

### Expected behavior

<!-- What do you think should happen? -->

### Actual behavior

<!-- What actually happens? -->

### How to reproduce

<!--

Your best chance of getting this bug looked at quickly is to provide a REPOSITORY that can be cloned and run.

You can fork https://github.com/electron/electron-quick-start and include a link to the branch with your changes.

If you provide a URL, please list the commands required to clone/setup/run your repo e.g.

  $ git clone $YOUR_URL -b $BRANCH
  $ npm install
  $ npm start || electron .

-->

If you believe that you have found a bug in Electron, please fill out this form to the best of your ability.

The two most important pieces of information needed to evaluate the report are a description of the bug and a simple test case to recreate it. It easier to fix a bug if it can be reproduced.

See How to create a Minimal, Complete, and Verifiable example.

Triaging a Bug Report

It's common for open issues to involve discussion. Some contributors may have differing opinions, including whether the behavior is a bug or feature. This discussion is part of the process and should be kept focused, helpful, and professional.

Terse responses that provide neither additional context nor supporting detail are not helpful or professional. To many, such responses are annoying and unfriendly.

Contributors are encouraged to solve issues collaboratively and help one another make progress. If encounter an issue that you feel is invalid, or which contains incorrect information, explain why you feel that way with additional supporting context, and be willing to be convinced that you may be wrong. By doing so, we can often reach the correct outcome faster.

Resolving a Bug Report

Most issues are resolved by opening a pull request. The process for opening and reviewing a pull request is similar to that of opening and triaging issues, but carries with it a necessary review and approval workflow that ensures that the proposed changes meet the minimal quality and functional guidelines of the Electron project.


JumpListCategory Object

  • type String (optional) - One of the following:

    • tasks - Items in this category will be placed into the standard Tasks category. There can be only one such category, and it will always be displayed at the bottom of the Jump List.
    • frequent - Displays a list of files frequently opened by the app, the name of the category and its items are set by Windows.
    • recent - Displays a list of files recently opened by the app, the name of the category and its items are set by Windows. Items may be added to this category indirectly using app.addRecentDocument(path).
    • custom - Displays tasks or file links, name must be set by the app.
  • name String (optional) - Must be set if type is custom, otherwise it should be omitted.
  • items JumpListItem - Array of JumpListItem objects if type is tasks or custom, otherwise it should be omitted.

Note: If a JumpListCategory object has neither the type nor the name property set then its type is assumed to be tasks. If the name property is set but the type property is omitted then the type is assumed to be custom.


JumpListItem Object

  • type String (optional) - One of the following:

    • task - A task will launch an app with specific arguments.
    • separator - Can be used to separate items in the standard Tasks category.
    • file - A file link will open a file using the app that created the Jump List, for this to work the app must be registered as a handler for the file type (though it doesn't have to be the default handler).
  • path String (optional) - Path of the file to open, should only be set if type is file.
  • program String (optional) - Path of the program to execute, usually you should specify process.execPath which opens the current program. Should only be set if type is task.
  • args String (optional) - The command line arguments when program is executed. Should only be set if type is task.
  • title String (optional) - The text to be displayed for the item in the Jump List. Should only be set if type is task.
  • description String (optional) - Description of the task (displayed in a tooltip). Should only be set if type is task.
  • iconPath String (optional) - The absolute path to an icon to be displayed in a Jump List, which can be an arbitrary resource file that contains an icon (e.g. .ico, .exe, .dll). You can usually specify process.execPath to show the program icon.
  • iconIndex Number (optional) - The index of the icon in the resource file. If a resource file contains multiple icons this value can be used to specify the zero-based index of the icon that should be displayed for this task. If a resource file contains only one icon, this property should be set to zero.

Keyboard Shortcuts

Configure local and global keyboard shortcuts

Local Shortcuts

You can use the Menu module to configure keyboard shortcuts that will be triggered only when the app is focused. To do so, specify an accelerator property when creating a MenuItem.

const { Menu, MenuItem } = require('electron')
const menu = new Menu()

menu.append(new MenuItem({
  label: 'Print',
  accelerator: 'CmdOrCtrl+P',
  click: () => { console.log('time to print stuff') }
}))

You can configure different key combinations based on the user's operating system.

{
  accelerator: process.platform === 'darwin' ? 'Alt+Cmd+I' : 'Ctrl+Shift+I'
}

Global Shortcuts

You can use the globalShortcut module to detect keyboard events even when the application does not have keyboard focus.

const { app, globalShortcut } = require('electron')

app.on('ready', () => {
  globalShortcut.register('CommandOrControl+X', () => {
    console.log('CommandOrControl+X is pressed')
  })
})

Shortcuts within a BrowserWindow

If you want to handle keyboard shortcuts for a BrowserWindow, you can use the keyup and keydown event listeners on the window object inside the renderer process.

window.addEventListener('keyup', doSomething, true)

Note the third parameter true which means the listener will always receive key presses before other listeners so they can't have stopPropagation() called on them.

The before-input-event event is emitted before dispatching keydown and keyup events in the page. It can be used to catch and handle custom shortcuts that are not visible in the menu.

If you don't want to do manual shortcut parsing there are libraries that do advanced key detection such as mousetrap.

Mousetrap.bind('4', () => { console.log('4') })
Mousetrap.bind('?', () => { console.log('show shortcuts!') })
Mousetrap.bind('esc', () => { console.log('escape') }, 'keyup')

// combinations
Mousetrap.bind('command+shift+k', () => { console.log('command shift k') })

// map multiple combinations to the same callback
Mousetrap.bind(['command+k', 'ctrl+k'], () => {
  console.log('command k or control k')

  // return false to prevent default behavior and stop event from bubbling
  return false
})

// gmail style sequences
Mousetrap.bind('g i', () => { console.log('go to inbox') })
Mousetrap.bind('* a', () => { console.log('select all') })

// konami code!
Mousetrap.bind('up up down down left right left right b a enter', () => {
  console.log('konami code')
})

Custom Linux Desktop Launcher Actions

On many Linux environments, you can add custom entries to its launcher by modifying the .desktop file. For Canonical's Unity documentation, see Adding Shortcuts to a Launcher. For details on a more generic implementation, see the freedesktop.org Specification.

Launcher shortcuts of Audacious:

audacious

Generally speaking, shortcuts are added by providing a Name and Exec property for each entry in the shortcuts menu. Unity will execute the Exec field once clicked by the user. The format is as follows:

Actions=PlayPause;Next;Previous

[Desktop Action PlayPause]
Name=Play-Pause
Exec=audacious -t
OnlyShowIn=Unity;

[Desktop Action Next]
Name=Next
Exec=audacious -f
OnlyShowIn=Unity;

[Desktop Action Previous]
Name=Previous
Exec=audacious -r
OnlyShowIn=Unity;

Unity's preferred way of telling your application what to do is to use parameters. You can find these in your app in the global variable process.argv.


Locales

Locale values returned by app.getLocale().

Electron uses Chromium's l10n_util library to fetch the locale. Possible values are listed below:

Language Code Language Name
af Afrikaans
am Amharic
ar Arabic
az Azerbaijani
be Belarusian
bg Bulgarian
bh Bihari
bn Bengali
br Breton
bs Bosnian
ca Catalan
co Corsican
cs Czech
cy Welsh
da Danish
de German
de-AT German (Austria)
de-CH German (Switzerland)
de-DE German (Germany)
el Greek
en English
en-AU English (Australia)
en-CA English (Canada)
en-GB English (UK)
en-NZ English (New Zealand)
en-US English (US)
en-ZA English (South Africa)
eo Esperanto
es Spanish
es-419 Spanish (Latin America)
et Estonian
eu Basque
fa Persian
fi Finnish
fil Filipino
fo Faroese
fr French
fr-CA French (Canada)
fr-CH French (Switzerland)
fr-FR French (France)
fy Frisian
ga Irish
gd Scots Gaelic
gl Galician
gn Guarani
gu Gujarati
ha Hausa
haw Hawaiian
he Hebrew
hi Hindi
hr Croatian
hu Hungarian
hy Armenian
ia Interlingua
id Indonesian
is Icelandic
it Italian
it-CH Italian (Switzerland)
it-IT Italian (Italy)
ja Japanese
jw Javanese
ka Georgian
kk Kazakh
km Cambodian
kn Kannada
ko Korean
ku Kurdish
ky Kyrgyz
la Latin
ln Lingala
lo Laothian
lt Lithuanian
lv Latvian
mk Macedonian
ml Malayalam
mn Mongolian
mo Moldavian
mr Marathi
ms Malay
mt Maltese
nb Norwegian (Bokmal)
ne Nepali
nl Dutch
nn Norwegian (Nynorsk)
no Norwegian
oc Occitan
om Oromo
or Oriya
pa Punjabi
pl Polish
ps Pashto
pt Portuguese
pt-BR Portuguese (Brazil)
pt-PT Portuguese (Portugal)
qu Quechua
rm Romansh
ro Romanian
ru Russian
sd Sindhi
sh Serbo-Croatian
si Sinhalese
sk Slovak
sl Slovenian
sn Shona
so Somali
sq Albanian
sr Serbian
st Sesotho
su Sundanese
sv Swedish
sw Swahili
ta Tamil
te Telugu
tg Tajik
th Thai
ti Tigrinya
tk Turkmen
to Tonga
tr Turkish
tt Tatar
tw Twi
ug Uighur
uk Ukrainian
ur Urdu
uz Uzbek
vi Vietnamese
xh Xhosa
yi Yiddish
yo Yoruba
zh Chinese
zh-CN Chinese (Simplified)
zh-TW Chinese (Traditional)
zu Zulu

Mac App Store Submission Guide

Since v0.34.0, Electron allows submitting packaged apps to the Mac App Store (MAS). This guide provides information on: how to submit your app and the limitations of the MAS build.

Note: Submitting an app to Mac App Store requires enrolling Apple Developer Program, which costs money.

How to Submit Your App

The following steps introduce a simple way to submit your app to Mac App Store. However, these steps do not ensure your app will be approved by Apple; you still need to read Apple's Submitting Your App guide on how to meet the Mac App Store requirements.

Get Certificate

To submit your app to the Mac App Store, you first must get a certificate from Apple. You can follow these existing guides on web.

Get Team ID

Before signing your app, you need to know the Team ID of your account. To locate your Team ID, Sign in to Apple Developer Center, and click Membership in the sidebar. Your Team ID appears in the Membership Information section under the team name.

Sign Your App

After finishing the preparation work, you can package your app by following Application Distribution, and then proceed to signing your app.

First, you have to add a ElectronTeamID key to your app's Info.plist, which has your Team ID as value:

<plist version="1.0">
<dict>
  ...
  <key>ElectronTeamID</key>
  <string>TEAM_ID</string>
</dict>
</plist>

Then, you need to prepare three entitlements files.

child.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>com.apple.security.app-sandbox</key>
    <true/>
    <key>com.apple.security.inherit</key>
    <true/>
  </dict>
</plist>

parent.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>com.apple.security.app-sandbox</key>
    <true/>
    <key>com.apple.security.application-groups</key>
    <string>TEAM_ID.your.bundle.id</string>
  </dict>
</plist>

loginhelper.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>com.apple.security.app-sandbox</key>
    <true/>
  </dict>
</plist>

You have to replace TEAM_ID with your Team ID, and replace your.bundle.id with the Bundle ID of your app.

And then sign your app with the following script:

#!/bin/bash

# Name of your app.
APP="YourApp"
# The path of your app to sign.
APP_PATH="/path/to/YourApp.app"
# The path to the location you want to put the signed package.
RESULT_PATH="~/Desktop/$APP.pkg"
# The name of certificates you requested.
APP_KEY="3rd Party Mac Developer Application: Company Name (APPIDENTITY)"
INSTALLER_KEY="3rd Party Mac Developer Installer: Company Name (APPIDENTITY)"
# The path of your plist files.
CHILD_PLIST="/path/to/child.plist"
PARENT_PLIST="/path/to/parent.plist"
LOGINHELPER_PLIST="/path/to/loginhelper.plist"

FRAMEWORKS_PATH="$APP_PATH/Contents/Frameworks"

codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Electron Framework"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Libraries/libffmpeg.dylib"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Libraries/libnode.dylib"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper.app/Contents/MacOS/$APP Helper"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper.app/"
codesign -s "$APP_KEY" -f --entitlements "$LOGINHELPER_PLIST" "$APP_PATH/Contents/Library/LoginItems/$APP Login Helper.app/Contents/MacOS/$APP Login Helper"
codesign -s "$APP_KEY" -f --entitlements "$LOGINHELPER_PLIST" "$APP_PATH/Contents/Library/LoginItems/$APP Login Helper.app/"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$APP_PATH/Contents/MacOS/$APP"
codesign -s "$APP_KEY" -f --entitlements "$PARENT_PLIST" "$APP_PATH"

productbuild --component "$APP_PATH" /Applications --sign "$INSTALLER_KEY" "$RESULT_PATH"

If you are new to app sandboxing under macOS, you should also read through Apple's Enabling App Sandbox to have a basic idea, then add keys for the permissions needed by your app to the entitlements files.

Apart from manually signing your app, you can also choose to use the electron-osx-sign module to do the job.

Sign Native Modules

Native modules used in your app also need to be signed. If using electron-osx-sign, be sure to include the path to the built binaries in the argument list:

electron-osx-sign YourApp.app YourApp.app/Contents/Resources/app/node_modules/nativemodule/build/release/nativemodule

Also note that native modules may have intermediate files produced which should not be included (as they would also need to be signed). If you use electron-packager before version 8.1.0, add --ignore=.+\.o$ to your build step to ignore these files. Versions 8.1.0 and later ignores those files by default.

Upload Your App

After signing your app, you can use Application Loader to upload it to iTunes Connect for processing, making sure you have created a record before uploading.

Limitations of MAS Build

In order to satisfy all requirements for app sandboxing, the following modules have been disabled in the MAS build:

  • crashReporter
  • autoUpdater

and the following behaviors have been changed:

  • Video capture may not work for some machines.
  • Certain accessibility features may not work.
  • Apps will not be aware of DNS changes.

Also, due to the usage of app sandboxing, the resources which can be accessed by the app are strictly limited; you can read App Sandboxing for more information.

Additional Entitlements

Depending on which Electron APIs your app uses, you may need to add additional entitlements to your parent.plist file to be able to use these APIs from your app's Mac App Store build.

Network Access

Enable outgoing network connections to allow your app to connect to a server:

<key>com.apple.security.network.client</key>
<true/>

Enable incoming network connections to allow your app to open a network listening socket:

<key>com.apple.security.network.server</key>
<true/>

See the Enabling Network Access documentation for more details.

dialog.showOpenDialog

<key>com.apple.security.files.user-selected.read-only</key>
<true/>

See the Enabling User-Selected File Access documentation for more details.

dialog.showSaveDialog

<key>com.apple.security.files.user-selected.read-write</key>
<true/>

See the Enabling User-Selected File Access documentation for more details.

Cryptographic Algorithms Used by Electron

Depending on the country and region you are located, Mac App Store may require documenting the cryptographic algorithms used in your app, and even ask you to submit a copy of U.S. Encryption Registration (ERN) approval.

Electron uses following cryptographic algorithms:

On how to get the ERN approval, you can reference the article: How to legally submit an app to Apple’s App Store when it uses encryption (or how to obtain an ERN).


MacOS Dock

Electron has APIs to configure the app's icon in the macOS Dock. A macOS-only API exists to create a custom dock menu, but Electron also uses the app's dock icon to implement cross-platform features like recent documents and application progress.

The custom dock is commonly used to add shortcuts to tasks the user wouldn't want to open the whole app window for.

Dock menu of Terminal.app:

Dock Menu

To set your custom dock menu, you can use the app.dock.setMenu API, which is only available on macOS:

const { app, Menu } = require('electron')

const dockMenu = Menu.buildFromTemplate([
  {
    label: 'New Window',
    click () { console.log('New Window') }
  }, {
    label: 'New Window with Settings',
    submenu: [
      { label: 'Basic' },
      { label: 'Pro' }
    ]
  },
  { label: 'New Command...' }
])

app.dock.setMenu(dockMenu)

MemoryInfo Object

  • pid Integer - Process id of the process.
  • workingSetSize Integer - The amount of memory currently pinned to actual physical RAM.
  • peakWorkingSetSize Integer - The maximum amount of memory that has ever been pinned to actual physical RAM. On macOS its value will always be 0.
  • privateBytes Integer - The amount of memory not shared by other processes, such as JS heap or HTML content.
  • sharedBytes Integer - The amount of memory shared between processes, typically memory consumed by the Electron code itself

Note that all statistics are reported in Kilobytes.


MemoryUsageDetails Object

  • count Number
  • size Number
  • liveSize Number

Class: Menu

Create native application menus and context menus.

Process: Main

new Menu()

Creates a new menu.

Static Methods

The menu class has the following static methods:

  • menu Menu | null

Sets menu as the application menu on macOS. On Windows and Linux, the menu will be set as each window's top menu.

Passing null will remove the menu bar on Windows and Linux but has no effect on macOS.

Note: This API has to be called after the ready event of app module.

Returns Menu | null - The application menu, if set, or null, if not set.

Note: The returned Menu instance doesn't support dynamic addition or removal of menu items. Instance properties can still be dynamically modified.

  • action String

Sends the action to the first responder of application. This is used for emulating default macOS menu behaviors. Usually you would use the role property of a MenuItem.

See the macOS Cocoa Event Handling Guide for more information on macOS' native actions.

  • template MenuItemConstructorOptions[]

Returns Menu

Generally, the template is an array of options for constructing a MenuItem. The usage can be referenced above.

You can also attach other fields to the element of the template and they will become properties of the constructed menu items.

Instance Methods

The menu object has the following instance methods:

  • options Object

    • window BrowserWindow (optional) - Default is the focused window.
    • x Number (optional) - Default is the current mouse cursor position. Must be declared if y is declared.
    • y Number (optional) - Default is the current mouse cursor position. Must be declared if x is declared.
    • positioningItem Number (optional) macOS - The index of the menu item to be positioned under the mouse cursor at the specified coordinates. Default is -1.
    • callback Function (optional) - Called when menu is closed.

Pops up this menu as a context menu in the BrowserWindow.

  • browserWindow BrowserWindow (optional) - Default is the focused window.

Closes the context menu in the browserWindow.

Appends the menuItem to the menu.

  • id String

Returns MenuItem the item with the specified id

Inserts the menuItem to the pos position of the menu.

Instance Events

Objects created with new Menu emit the following events:

Note: Some events are only available on specific operating systems and are labeled as such.

Event: 'menu-will-show'

Returns:

  • event Event

Emitted when menu.popup() is called.

Event: 'menu-will-close'

Returns:

  • event Event

Emitted when a popup is closed either manually or with menu.closePopup().

Instance Properties

menu objects also have the following properties:

A MenuItem[] array containing the menu's items.

Each Menu consists of multiple MenuItems and each MenuItem can have a submenu.

Instance Events

Objects created with new Menu or returned by Menu.buildFromTemplate emit the following events:

Examples

The Menu class is only available in the main process, but you can also use it in the render process via the remote module.

Main process

An example of creating the application menu in the main process with the simple template API:

const {app, Menu} = require('electron')

const template = [
  {
    label: 'Edit',
    submenu: [
      {role: 'undo'},
      {role: 'redo'},
      {type: 'separator'},
      {role: 'cut'},
      {role: 'copy'},
      {role: 'paste'},
      {role: 'pasteandmatchstyle'},
      {role: 'delete'},
      {role: 'selectall'}
    ]
  },
  {
    label: 'View',
    submenu: [
      {role: 'reload'},
      {role: 'forcereload'},
      {role: 'toggledevtools'},
      {type: 'separator'},
      {role: 'resetzoom'},
      {role: 'zoomin'},
      {role: 'zoomout'},
      {type: 'separator'},
      {role: 'togglefullscreen'}
    ]
  },
  {
    role: 'window',
    submenu: [
      {role: 'minimize'},
      {role: 'close'}
    ]
  },
  {
    role: 'help',
    submenu: [
      {
        label: 'Learn More',
        click () { require('electron').shell.openExternal('https://electronjs.org') }
      }
    ]
  }
]

if (process.platform === 'darwin') {
  template.unshift({
    label: app.getName(),
    submenu: [
      {role: 'about'},
      {type: 'separator'},
      {role: 'services', submenu: []},
      {type: 'separator'},
      {role: 'hide'},
      {role: 'hideothers'},
      {role: 'unhide'},
      {type: 'separator'},
      {role: 'quit'}
    ]
  })

  // Edit menu
  template[1].submenu.push(
    {type: 'separator'},
    {
      label: 'Speech',
      submenu: [
        {role: 'startspeaking'},
        {role: 'stopspeaking'}
      ]
    }
  )

  // Window menu
  template[3].submenu = [
    {role: 'close'},
    {role: 'minimize'},
    {role: 'zoom'},
    {type: 'separator'},
    {role: 'front'}
  ]
}

const menu = Menu.buildFromTemplate(template)
Menu.setApplicationMenu(menu)

Render process

Below is an example of creating a menu dynamically in a web page (render process) by using the remote module, and showing it when the user right clicks the page:

<!-- index.html -->
<script>
const {remote} = require('electron')
const {Menu, MenuItem} = remote

const menu = new Menu()
menu.append(new MenuItem({label: 'MenuItem1', click() { console.log('item 1 clicked') }}))
menu.append(new MenuItem({type: 'separator'}))
menu.append(new MenuItem({label: 'MenuItem2', type: 'checkbox', checked: true}))

window.addEventListener('contextmenu', (e) => {
  e.preventDefault()
  menu.popup({window: remote.getCurrentWindow()})
}, false)
</script>

Notes on macOS Application Menu

macOS has a completely different style of application menu from Windows and Linux. Here are some notes on making your app's menu more native-like.

Standard Menus

On macOS there are many system-defined standard menus, like the Services and Windows menus. To make your menu a standard menu, you should set your menu's role to one of the following and Electron will recognize them and make them become standard menus:

  • window
  • help
  • services

Standard Menu Item Actions

macOS has provided standard actions for some menu items, like About xxx, Hide xxx, and Hide Others. To set the action of a menu item to a standard action, you should set the role attribute of the menu item.

On macOS the label of the application menu's first item is always your app's name, no matter what label you set. To change it, modify your app bundle's Info.plist file. See About Information Property List Files for more information.

Setting Menu for Specific Browser Window (Linux Windows)

The setMenu method of browser windows can set the menu of certain browser windows.

You can make use of before, after, beforeGroupContaining, afterGroupContaining and id to control how the item will be placed when building a menu with Menu.buildFromTemplate.

  • before - Inserts this item before the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu. Also implies that the menu item in question should be placed in the same “group” as the item.
  • after - Inserts this item after the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu. Also implies that the menu item in question should be placed in the same “group” as the item.
  • beforeGroupContaining - Provides a means for a single context menu to declare the placement of their containing group before the containing group of the item with the specified label.
  • afterGroupContaining - Provides a means for a single context menu to declare the placement of their containing group after the containing group of the item with the specified label.

By default, items will be inserted in the order they exist in the template unless one of the specified positioning keywords is used.

Examples

Template:

[
  { id: '1', label: 'one' },
  { id: '2', label: 'two' },
  { id: '3', label: 'three' },
  { id: '4', label: 'four' }
]

Menu:

- 1
- 2
- 3
- 4

Template:

[
  { id: '1', label: 'one' },
  { type: 'separator' },
  { id: '3', label: 'three', beforeGroupContaining: ['1'] },
  { id: '4', label: 'four', afterGroupContaining: ['2'] },
  { type: 'separator' },
  { id: '2', label: 'two' }
]

Menu:

- 3
- 4
- ---
- 1
- ---
- 2

Template:

[
  { id: '1', label: 'one', after: ['3'] },
  { id: '2', label: 'two', before: ['1'] },
  { id: '3', label: 'three' }
]

Menu:

- ---
- 3
- 2
- 1

Class: MenuItem

Add items to native application menus and context menus.

Process: Main

See Menu for examples.

new MenuItem(options)

  • options Object

    • click Function (optional) - Will be called with click(menuItem, browserWindow, event) when the menu item is clicked.

    • role String (optional) - Define the action of the menu item, when specified the click property will be ignored. See roles.
    • type String (optional) - Can be normal, separator, submenu, checkbox or radio.
    • label String (optional)
    • sublabel String (optional)
    • accelerator Accelerator (optional)
    • icon (NativeImage | String) (optional)
    • enabled Boolean (optional) - If false, the menu item will be greyed out and unclickable.
    • visible Boolean (optional) - If false, the menu item will be entirely hidden.
    • checked Boolean (optional) - Should only be specified for checkbox or radio type menu items.
    • submenu (MenuItemConstructorOptions[] | Menu) (optional) - Should be specified for submenu type menu items. If submenu is specified, the type: 'submenu' can be omitted. If the value is not a Menu then it will be automatically converted to one using Menu.buildFromTemplate.
    • id String (optional) - Unique within a single menu. If defined then it can be used as a reference to this item by the position attribute.
    • position String (optional) - This field allows fine-grained definition of the specific location within a given menu.

Roles

Roles allow menu items to have predefined behaviors.

It is best to specify role for any menu item that matches a standard role, rather than trying to manually implement the behavior in a click function. The built-in role behavior will give the best native experience.

The label and accelerator values are optional when using a role and will default to appropriate values for each platform.

The role property can have following values:

  • undo
  • redo
  • cut
  • copy
  • paste
  • pasteAndMatchStyle
  • selectAll
  • delete
  • minimize - Minimize current window.
  • close - Close current window.
  • quit- Quit the application.
  • reload - Reload the current window.
  • forceReload - Reload the current window ignoring the cache.
  • toggleDevTools - Toggle developer tools in the current window.
  • toggleFullScreen- Toggle full screen mode on the current window.
  • resetZoom - Reset the focused page's zoom level to the original size.
  • zoomIn - Zoom in the focused page by 10%.
  • zoomOut - Zoom out the focused page by 10%.
  • editMenu - Whole default "Edit" menu (Undo, Copy, etc.).
  • windowMenu - Whole default "Window" menu (Minimize, Close, etc.).

The following additional roles are available on macOS:

  • about - Map to the orderFrontStandardAboutPanel action.
  • hide - Map to the hide action.
  • hideOthers - Map to the hideOtherApplications action.
  • unhide - Map to the unhideAllApplications action.
  • startSpeaking - Map to the startSpeaking action.
  • stopSpeaking - Map to the stopSpeaking action.
  • front - Map to the arrangeInFront action.
  • zoom - Map to the performZoom action.
  • toggleTabBar - Map to the toggleTabBar action.
  • selectNextTab - Map to the selectNextTab action.
  • selectPreviousTab - Map to the selectPreviousTab action.
  • mergeAllWindows - Map to the mergeAllWindows action.
  • moveTabToNewWindow - Map to the moveTabToNewWindow action.
  • window - The submenu is a "Window" menu.
  • help - The submenu is a "Help" menu.
  • services - The submenu is a "Services" menu.
  • recentDocuments - The submenu is an "Open Recent" menu.
  • clearRecentDocuments - Map to the clearRecentDocuments action.

When specifying a role on macOS, label and accelerator are the only options that will affect the menu item. All other options will be ignored. Lowercase role, e.g. toggledevtools, is still supported.

Nota Bene: The enabled and visibility properties are not available for top-level menu items in the tray on MacOS.

Instance Properties

The following properties are available on instances of MenuItem:

A Boolean indicating whether the item is enabled, this property can be dynamically changed.

A Boolean indicating whether the item is visible, this property can be dynamically changed.

A Boolean indicating whether the item is checked, this property can be dynamically changed.

A checkbox menu item will toggle the checked property on and off when selected.

A radio menu item will turn on its checked property when clicked, and will turn off that property for all adjacent items in the same menu.

You can add a click function for additional behavior.

A String representing the menu items visible label.

A Function that is fired when the MenuItem receives a click event.


MimeTypedBuffer Object

  • mimeType String - The mimeType of the Buffer that you are sending
  • data Buffer - The actual Buffer content

Mojave Dark Mode

In macOS 10.14 Mojave, Apple introduced a new system-wide dark mode for all macOS computers. By default Electron apps do not automatically adjust their UI and native interfaces to the dark mode setting when it's enabled. This is primarily due to Apple's own guidelines saying you shouldn't use the dark mode native interfaces if your app's own interfaces don't support dark mode themselves.

If your app does have a dark mode, you can make your Electron app follow the system-wide dark mode setting.

Automatically updating the native interfaces

"Native Interfaces" include the file picker, window border, dialogs, context menus and more; basically anything where the UI comes from macOS and not your app. In order to make these interfaces update to dark mode automatically, you need to set the NSRequiresAquaSystemAppearance key in your app's Info.plist file to false. E.g.

<plist>
<dict>
  ...
  <key>NSRequiresAquaSystemAppearance</key>
  <false />
  ...
</dict>
</plist>

If you are using electron-packager >= 12.2.0 or electron-forge >= 6 you can set the darwinDarkModeSupport option when packaging and this key will be set for you.

If you are using electron-builder >= 20.37.0 you can set the darkModeSupport option.

Automatically updating your own interfaces

If your app has its own dark mode you should toggle it on and off in sync with the system's dark mode setting. You can do this by listening for the theme changed event on Electron's systemPreferences module. E.g.

const { systemPreferences } = require('electron')

systemPreferences.subscribeNotification(
  'AppleInterfaceThemeChangedNotification',
  function theThemeHasChanged () {
    updateMyAppTheme(systemPreferences.isDarkMode())
  }
)

Multithreading

With Web Workers, it is possible to run JavaScript in OS-level threads.

Multi-threaded Node.js

It is possible to use Node.js features in Electron's Web Workers, to do so the nodeIntegrationInWorker option should be set to true in webPreferences.

let win = new BrowserWindow({
  webPreferences: {
    nodeIntegrationInWorker: true
  }
})

The nodeIntegrationInWorker can be used independent of nodeIntegration, but sandbox must not be set to true.

Available APIs

All built-in modules of Node.js are supported in Web Workers, and asar archives can still be read with Node.js APIs. However none of Electron's built-in modules can be used in a multi-threaded environment.

Native Node.js modules

Any native Node.js module can be loaded directly in Web Workers, but it is strongly recommended not to do so. Most existing native modules have been written assuming single-threaded environment, using them in Web Workers will lead to crashes and memory corruptions.

Note that even if a native Node.js module is thread-safe it's still not safe to load it in a Web Worker because the process.dlopen function is not thread safe.

The only way to load a native module safely for now, is to make sure the app loads no native modules after the Web Workers get started.

process.dlopen = () => {
  throw new Error('Load native module is not safe')
}
let worker = new Worker('script.js')

Native File Drag & Drop

Certain kinds of applications that manipulate files might want to support the operating system's native file drag & drop feature. Dragging files into web content is common and supported by many websites. Electron additionally supports dragging files and content out from web content into the operating system's world.

To implement this feature in your app, you need to call webContents.startDrag(item) API in response to the ondragstart event.

In your renderer process, handle the ondragstart event and forward the information to your main process.

<a href="#" id="drag">item</a>
<script type="text/javascript" charset="utf-8">
  document.getElementById('drag').ondragstart = (event) => {
    event.preventDefault()
    ipcRenderer.send('ondragstart', '/path/to/item')
  }
</script>

Then, in the main process, augment the event with a path to the file that is being dragged and an icon.

const { ipcMain } = require('electron')

ipcMain.on('ondragstart', (event, filePath) => {
  event.sender.startDrag({
    file: filePath,
    icon: '/path/to/icon.png'
  })
})

nativeImage

Create tray, dock, and application icons using PNG or JPG files.

Process: Main, Renderer

In Electron, for the APIs that take images, you can pass either file paths or NativeImage instances. An empty image will be used when null is passed.

For example, when creating a tray or setting a window's icon, you can pass an image file path as a String:

const {BrowserWindow, Tray} = require('electron')

const appIcon = new Tray('/Users/somebody/images/icon.png')
let win = new BrowserWindow({icon: '/Users/somebody/images/window.png'})
console.log(appIcon, win)

Or read the image from the clipboard which returns a NativeImage:

const {clipboard, Tray} = require('electron')
const image = clipboard.readImage()
const appIcon = new Tray(image)
console.log(appIcon)

Supported Formats

Currently PNG and JPEG image formats are supported. PNG is recommended because of its support for transparency and lossless compression.

On Windows, you can also load ICO icons from file paths. For best visual quality it is recommended to include at least the following sizes in the:

  • Small icon
  • 16x16 (100% DPI scale)
  • 20x20 (125% DPI scale)
  • 24x24 (150% DPI scale)
  • 32x32 (200% DPI scale)
  • Large icon
  • 32x32 (100% DPI scale)
  • 40x40 (125% DPI scale)
  • 48x48 (150% DPI scale)
  • 64x64 (200% DPI scale)
  • 256x256

Check the Size requirements section in this article.

High Resolution Image

On platforms that have high-DPI support such as Apple Retina displays, you can append @2x after image's base filename to mark it as a high resolution image.

For example if icon.png is a normal image that has standard resolution, then icon@2x.png will be treated as a high resolution image that has double DPI density.

If you want to support displays with different DPI densities at the same time, you can put images with different sizes in the same folder and use the filename without DPI suffixes. For example:

images/
├── icon.png
├── icon@2x.png
└── icon@3x.png
const {Tray} = require('electron')
let appIcon = new Tray('/Users/somebody/images/icon.png')
console.log(appIcon)

Following suffixes for DPI are also supported:

  • @1x
  • @1.25x
  • @1.33x
  • @1.4x
  • @1.5x
  • @1.8x
  • @2x
  • @2.5x
  • @3x
  • @4x
  • @5x

Template Image

Template images consist of black and an alpha channel. Template images are not intended to be used as standalone images and are usually mixed with other content to create the desired final appearance.

The most common case is to use template images for a menu bar icon so it can adapt to both light and dark menu bars.

Note: Template image is only supported on macOS.

To mark an image as a template image, its filename should end with the word Template. For example:

  • xxxTemplate.png
  • xxxTemplate@2x.png

Methods

The nativeImage module has the following methods, all of which return an instance of the NativeImage class:

nativeImage.createEmpty()

Returns NativeImage

Creates an empty NativeImage instance.

nativeImage.createFromPath(path)

  • path String

Returns NativeImage

Creates a new NativeImage instance from a file located at path. This method returns an empty image if the path does not exist, cannot be read, or is not a valid image.

const nativeImage = require('electron').nativeImage

let image = nativeImage.createFromPath('/Users/somebody/images/icon.png')
console.log(image)

nativeImage.createFromBuffer(buffer[, options])

  • buffer Buffer
  • options Object (optional)

    • width Integer (optional) - Required for bitmap buffers.
    • height Integer (optional) - Required for bitmap buffers.
    • scaleFactor Double (optional) - Defaults to 1.0.

Returns NativeImage

Creates a new NativeImage instance from buffer.

nativeImage.createFromDataURL(dataURL)

  • dataURL String

Returns NativeImage

Creates a new NativeImage instance from dataURL.

nativeImage.createFromNamedImage(imageName[, hslShift]) macOS

  • imageName String
  • hslShift Number[]

Returns NativeImage

Creates a new NativeImage instance from the NSImage that maps to the given image name. See NSImageName for a list of possible values.

The hslShift is applied to the image with the following rules

  • hsl_shift[0] (hue): The absolute hue value for the image - 0 and 1 map to 0 and 360 on the hue color wheel (red).
  • hsl_shift[1] (saturation): A saturation shift for the image, with the following key values: 0 = remove all color. 0.5 = leave unchanged. 1 = fully saturate the image.
  • hsl_shift[2] (lightness): A lightness shift for the image, with the following key values: 0 = remove all lightness (make all pixels black). 0.5 = leave unchanged. 1 = full lightness (make all pixels white).

This means that [-1, 0, 1] will make the image completely white and [-1, 1, 0] will make the image completely black.

Class: NativeImage

Natively wrap images such as tray, dock, and application icons.

Process: Main, Renderer

Instance Methods

The following methods are available on instances of the NativeImage class:

image.toPNG([options])

  • options Object (optional)

    • scaleFactor Double (optional) - Defaults to 1.0.

Returns Buffer - A Buffer that contains the image's PNG encoded data.

image.toJPEG(quality)

  • quality Integer (required) - Between 0 - 100.

Returns Buffer - A Buffer that contains the image's JPEG encoded data.

image.toBitmap([options])

  • options Object (optional)

    • scaleFactor Double (optional) - Defaults to 1.0.

Returns Buffer - A Buffer that contains a copy of the image's raw bitmap pixel data.

image.toDataURL([options])

  • options Object (optional)

    • scaleFactor Double (optional) - Defaults to 1.0.

Returns String - The data URL of the image.

image.getBitmap([options])

  • options Object (optional)

    • scaleFactor Double (optional) - Defaults to 1.0.

Returns Buffer - A Buffer that contains the image's raw bitmap pixel data.

The difference between getBitmap() and toBitmap() is, getBitmap() does not copy the bitmap data, so you have to use the returned Buffer immediately in current event loop tick, otherwise the data might be changed or destroyed.

image.getNativeHandle() macOS

Returns Buffer - A Buffer that stores C pointer to underlying native handle of the image. On macOS, a pointer to NSImage instance would be returned.

Notice that the returned pointer is a weak pointer to the underlying native image instead of a copy, so you must ensure that the associated nativeImage instance is kept around.

image.isEmpty()

Returns Boolean - Whether the image is empty.

image.setTemplateImage(option)

  • option Boolean

Marks the image as a template image.

image.isTemplateImage()

Returns Boolean - Whether the image is a template image.

image.crop(rect)

  • rect Rectangle - The area of the image to crop.

Returns NativeImage - The cropped image.

image.resize(options)

  • options Object

    • width Integer (optional) - Defaults to the image's width.
    • height Integer (optional) - Defaults to the image's height.
    • quality String (optional) - The desired quality of the resize image. Possible values are good, better or best. The default is best. These values express a desired quality/speed tradeoff. They are translated into an algorithm-specific method that depends on the capabilities (CPU, GPU) of the underlying platform. It is possible for all three methods to be mapped to the same algorithm on a given platform.

Returns NativeImage - The resized image.

If only the height or the width are specified then the current aspect ratio will be preserved in the resized image.

image.getAspectRatio()

Returns Float - The image's aspect ratio.

image.addRepresentation(options)

  • options Object

    • scaleFactor Double - The scale factor to add the image representation for.
    • width Integer (optional) - Defaults to 0. Required if a bitmap buffer is specified as buffer.
    • height Integer (optional) - Defaults to 0. Required if a bitmap buffer is specified as buffer.
    • buffer Buffer (optional) - The buffer containing the raw image data.
    • dataURL String (optional) - The data URL containing either a base 64 encoded PNG or JPEG image.

Add an image representation for a specific scale factor. This can be used to explicitly add different scale factor representations to an image. This can be called on empty images.


net

Issue HTTP/HTTPS requests using Chromium's native networking library

Process: Main

The net module is a client-side API for issuing HTTP(S) requests. It is similar to the HTTP and HTTPS modules of Node.js but uses Chromium's native networking library instead of the Node.js implementation, offering better support for web proxies.

The following is a non-exhaustive list of why you may consider using the net module instead of the native Node.js modules:

  • Automatic management of system proxy configuration, support of the wpad protocol and proxy pac configuration files.
  • Automatic tunneling of HTTPS requests.
  • Support for authenticating proxies using basic, digest, NTLM, Kerberos or negotiate authentication schemes.
  • Support for traffic monitoring proxies: Fiddler-like proxies used for access control and monitoring.

The net module API has been specifically designed to mimic, as closely as possible, the familiar Node.js API. The API components including classes, methods, properties and event names are similar to those commonly used in Node.js.

For instance, the following example quickly shows how the net API might be used:

const {app} = require('electron')
app.on('ready', () => {
  const {net} = require('electron')
  const request = net.request('https://github.com')
  request.on('response', (response) => {
    console.log(`STATUS: ${response.statusCode}`)
    console.log(`HEADERS: ${JSON.stringify(response.headers)}`)
    response.on('data', (chunk) => {
      console.log(`BODY: ${chunk}`)
    })
    response.on('end', () => {
      console.log('No more data in response.')
    })
  })
  request.end()
})

By the way, it is almost identical to how you would normally use the HTTP/HTTPS modules of Node.js

The net API can be used only after the application emits the ready event. Trying to use the module before the ready event will throw an error.

Methods

The net module has the following methods:

net.request(options)

  • options (Object | String) - The ClientRequest constructor options.

Returns ClientRequest

Creates a ClientRequest instance using the provided options which are directly forwarded to the ClientRequest constructor. The net.request method would be used to issue both secure and insecure HTTP requests according to the specified protocol scheme in the options object.


netLog

Logging network events.

Process: Main

const {netLog} = require('electron')
console.log('Start recording net-logs')
netLog.startLogging('/path/to/net-log')
// After some network events
netLog.stopLogging(path => {
  console.log('Net-logs written to', path)
})

See --log-net-log to log network events throughout the app's lifecycle.

netLog.startLogging(path)

  • path String - File path to record network logs.

Starts recording network events to path.

netLog.stopLogging([callback])

  • callback Function (optional)

    • path String - File path to which network logs were recorded.

Stops recording network events. If not called, net logging will automatically end when app quits.

netLog.currentlyLogging

A Boolean property that indicates whether network logs are recorded.

netLog.currentlyLoggingPath

A String property that returns the path to the current log file.


Notification

Create OS desktop notifications

Process: Main

Using in the renderer process

If you want to show Notifications from a renderer process you should use the HTML5 Notification API

Class: Notification

Create OS desktop notifications

Process: Main

Notification is an EventEmitter.

It creates a new Notification with native properties as set by the options.

Static Methods

The Notification class has the following static methods:

Notification.isSupported()

Returns Boolean - Whether or not desktop notifications are supported on the current system

new Notification([options]) Experimental

  • options Object

    • title String - A title for the notification, which will be shown at the top of the notification window when it is shown.
    • subtitle String (optional) macOS - A subtitle for the notification, which will be displayed below the title.
    • body String - The body text of the notification, which will be displayed below the title or subtitle.
    • silent Boolean (optional) - Whether or not to emit an OS notification noise when showing the notification.
    • icon (String | NativeImage) (optional) - An icon to use in the notification.
    • hasReply Boolean (optional) macOS - Whether or not to add an inline reply option to the notification.
    • replyPlaceholder String (optional) macOS - The placeholder to write in the inline reply input field.
    • sound String (optional) macOS - The name of the sound file to play when the notification is shown.
    • actions NotificationAction[] (optional) macOS - Actions to add to the notification. Please read the available actions and limitations in the NotificationAction documentation.
    • closeButtonText String (optional) macOS - A custom title for the close button of an alert. An empty string will cause the default localized text to be used.

Instance Events

Objects created with new Notification emit the following events:

Note: Some events are only available on specific operating systems and are labeled as such.

Event: 'show'

Returns:

  • event Event

Emitted when the notification is shown to the user, note this could be fired multiple times as a notification can be shown multiple times through the show() method.

Event: 'click'

Returns:

  • event Event

Emitted when the notification is clicked by the user.

Event: 'close'

Returns:

  • event Event

Emitted when the notification is closed by manual intervention from the user.

This event is not guaranteed to be emitted in all cases where the notification is closed.

Event: 'reply' macOS

Returns:

  • event Event
  • reply String - The string the user entered into the inline reply field.

Emitted when the user clicks the "Reply" button on a notification with hasReply: true.

Event: 'action' macOS

Returns:

  • event Event
  • index Number - The index of the action that was activated.

Instance Methods

Objects created with new Notification have the following instance methods:

notification.show()

Immediately shows the notification to the user, please note this means unlike the HTML5 Notification implementation, instantiating a new Notification does not immediately show it to the user, you need to call this method before the OS will display it.

If the notification has been shown before, this method will dismiss the previously shown notification and create a new one with identical properties.

notification.close()

Dismisses the notification.

Playing Sounds

On macOS, you can specify the name of the sound you'd like to play when the notification is shown. Any of the default sounds (under System Preferences > Sound) can be used, in addition to custom sound files. Be sure that the sound file is copied under the app bundle (e.g., YourApp.app/Contents/Resources), or one of the following locations:

  • ~/Library/Sounds
  • /Library/Sounds
  • /Network/Library/Sounds
  • /System/Library/Sounds

See the NSSound docs for more information.


NotificationAction Object

  • type String - The type of action, can be button.
  • text String (optional) - The label for the given action.

Platform / Action Support

Action Type Platform Support Usage of text Default text Limitations
button macOS Used as the label for the button "Show" (or a localized string by system default if first of such button , otherwise empty) Only the first one is used. If multiple are provided, those beyond the first will be listed as additional actions (displayed when mouse active over the action button). Any such action also is incompatible with hasReply and will be ignored if hasReply is true .

Button support on macOS

In order for extra notification buttons to work on macOS your app must meet the following criteria.

  • App is signed
  • App has it's NSUserNotificationAlertStyle set to alert in the Info.plist.

If either of these requirements are not met the button won't appear.


Notifications (Windows, Linux, macOS)

All three operating systems provide means for applications to send notifications to the user. Electron conveniently allows developers to send notifications with the HTML5 Notification API, using the currently running operating system's native notification APIs to display it.

Note: Since this is an HTML5 API it is only available in the renderer process. If you want to show Notifications in the main process please check out the Notification module.

let myNotification = new Notification('Title', {
  body: 'Lorem Ipsum Dolor Sit Amet'
})

myNotification.onclick = () => {
  console.log('Notification clicked')
}

While code and user experience across operating systems are similar, there are subtle differences.

Windows

  • On Windows 10, a shortcut to your app with an Application User Model ID must be installed to the Start Menu.
  • On Windows 8.1 and Windows 8, a shortcut to your app with an Application User Model ID must be installed to the Start screen. Note, however, that it does not need to be pinned to the Start screen.
  • On Windows 7, notifications work via a custom implementation which visually resembles the native one on newer systems.

Electron attempts to automate the work around the Application User Model ID. When Electron is used together with the installation and update framework Squirrel, shortcuts will automatically be set correctly. Furthermore, Electron will detect that Squirrel was used and will automatically call app.setAppUserModelId() with the correct value. During development, you may have to call app.setAppUserModelId()(../api/app.md#appsetappusermodelidid-windows)] yourself.

Furthermore, in Windows 8, the maximum length for the notification body is 250 characters, with the Windows team recommending that notifications should be kept to 200 characters. That said, that limitation has been removed in Windows 10, with the Windows team asking developers to be reasonable. Attempting to send gigantic amounts of text to the API (thousands of characters) might result in instability.

Advanced Notifications

Later versions of Windows allow for advanced notifications, with custom templates, images, and other flexible elements. To send those notifications (from either the main process or the renderer process), use the userland module electron-windows-notifications, which uses native Node addons to send ToastNotification and TileNotification objects.

While notifications including buttons work with electron-windows-notifications, handling replies requires the use of electron-windows-interactive-notifications, which helps with registering the required COM components and calling your Electron app with the entered user data.

Quiet Hours / Presentation Mode

To detect whether or not you're allowed to send a notification, use the userland module electron-notification-state.

This allows you to determine ahead of time whether or not Windows will silently throw the notification away.

macOS

Notifications are straight-forward on macOS, but you should be aware of Apple's Human Interface guidelines regarding notifications.

Note that notifications are limited to 256 bytes in size and will be truncated if you exceed that limit.

Advanced Notifications

Later versions of macOS allow for notifications with an input field, allowing the user to quickly reply to a notification. In order to send notifications with an input field, use the userland module node-mac-notifier.

Do not disturb / Session State

To detect whether or not you're allowed to send a notification, use the userland module electron-notification-state.

This will allow you to detect ahead of time whether or not the notification will be displayed.

Linux

Notifications are sent using libnotify which can show notifications on any desktop environment that follows Desktop Notifications Specification, including Cinnamon, Enlightenment, Unity, GNOME, KDE.


Offscreen Rendering

Offscreen rendering lets you obtain the content of a browser window in a bitmap, so it can be rendered anywhere, for example on a texture in a 3D scene. The offscreen rendering in Electron uses a similar approach than the Chromium Embedded Framework project.

Two modes of rendering can be used and only the dirty area is passed in the 'paint' event to be more efficient. The rendering can be stopped, continued and the frame rate can be set. The specified frame rate is a top limit value, when there is nothing happening on a webpage, no frames are generated. The maximum frame rate is 60, because above that there is no benefit, only performance loss.

Note: An offscreen window is always created as a Frameless Window.

GPU accelerated

GPU accelerated rendering means that the GPU is used for composition. Because of that the frame has to be copied from the GPU which requires more performance, thus this mode is quite a bit slower than the other one. The benefit of this mode that WebGL and 3D CSS animations are supported.

Software output device

This mode uses a software output device for rendering in the CPU, so the frame generation is much faster, thus this mode is preferred over the GPU accelerated one.

To enable this mode GPU acceleration has to be disabled by calling the app.disableHardwareAcceleration() API.

Usage

const { app, BrowserWindow } = require('electron')

app.disableHardwareAcceleration()

let win

app.once('ready', () => {
  win = new BrowserWindow({
    webPreferences: {
      offscreen: true
    }
  })

  win.loadURL('http://github.com')
  win.webContents.on('paint', (event, dirty, image) => {
    // updateBitmap(dirty, image.getBitmap())
  })
  win.webContents.setFrameRate(30)
})

Online/Offline Event Detection

Online and offline event detection can be implemented in the renderer process using the navigator.onLine attribute, part of standard HTML5 API. The navigator.onLine attribute returns false if any network requests are guaranteed to fail i.e. definitely offline (disconnected from the network). It returns true in all other cases. Since all other conditions return true, one has to be mindful of getting false positives, as we cannot assume true value necessarily means that Electron can access the internet. Such as in cases where the computer is running a virtualization software that has virtual ethernet adapters that are always “connected.” Therefore, if you really want to determine the internet access status of Electron, you should develop additional means for checking.

Example:

main.js

const { app, BrowserWindow } = require('electron')

let onlineStatusWindow

app.on('ready', () => {
  onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
  onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})

online-status.html

<!DOCTYPE html>
<html>
<body>
<script>
  const alertOnlineStatus = () => {
    window.alert(navigator.onLine ? 'online' : 'offline')
  }

  window.addEventListener('online',  alertOnlineStatus)
  window.addEventListener('offline',  alertOnlineStatus)

  alertOnlineStatus()
</script>
</body>
</html>

There may be instances where you want to respond to these events in the main process as well. The main process however does not have a navigator object and thus cannot detect these events directly. Using Electron's inter-process communication utilities, the events can be forwarded to the main process and handled as needed, as shown in the following example.

main.js

const { app, BrowserWindow, ipcMain } = require('electron')
let onlineStatusWindow

app.on('ready', () => {
  onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
  onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})

ipcMain.on('online-status-changed', (event, status) => {
  console.log(status)
})

online-status.html

<!DOCTYPE html>
<html>
<body>
<script>
  const { ipcRenderer } = require('electron')
  const updateOnlineStatus = () => {
    ipcRenderer.send('online-status-changed', navigator.onLine ? 'online' : 'offline')
  }

  window.addEventListener('online',  updateOnlineStatus)
  window.addEventListener('offline',  updateOnlineStatus)

  updateOnlineStatus()
</script>
</body>
</html>

Point Object

  • x Number
  • y Number

powerMonitor

Monitor power state changes.

Process: Main

You cannot require or use this module until the ready event of the app module is emitted.

For example:

const electron = require('electron')
const {app} = electron

app.on('ready', () => {
  electron.powerMonitor.on('suspend', () => {
    console.log('The system is going to sleep')
  })
})

Events

The powerMonitor module emits the following events:

Event: 'suspend'

Emitted when the system is suspending.

Event: 'resume'

Emitted when system is resuming.

Event: 'on-ac' Windows

Emitted when the system changes to AC power.

Event: 'on-battery' Windows

Emitted when system changes to battery power.

Event: 'shutdown' Linux macOS

Emitted when the system is about to reboot or shut down. If the event handler invokes e.preventDefault(), Electron will attempt to delay system shutdown in order for the app to exit cleanly. If e.preventDefault() is called, the app should exit as soon as possible by calling something like app.quit().

Event: 'lock-screen' macOS Windows

Emitted when the system is about to lock the screen.

Event: 'unlock-screen' macOS Windows

Emitted as soon as the systems screen is unlocked.

Methods

The powerMonitor module has the following methods:

powerMonitor.querySystemIdleState(idleThreshold, callback)

  • idleThreshold Integer
  • callback Function

    • idleState String - Can be active, idle, locked or unknown

Calculate the system idle state. idleThreshold is the amount of time (in seconds) before considered idle. callback will be called synchronously on some systems and with an idleState argument that describes the system's state. locked is available on supported systems only.

powerMonitor.querySystemIdleTime(callback)

  • callback Function

    • idleTime Integer - Idle time in seconds

Calculate system idle time in seconds.


powerSaveBlocker

Block the system from entering low-power (sleep) mode.

Process: Main

For example:

const {powerSaveBlocker} = require('electron')

const id = powerSaveBlocker.start('prevent-display-sleep')
console.log(powerSaveBlocker.isStarted(id))

powerSaveBlocker.stop(id)

Methods

The powerSaveBlocker module has the following methods:

powerSaveBlocker.start(type)

  • type String - Power save blocker type.

    • prevent-app-suspension - Prevent the application from being suspended. Keeps system active but allows screen to be turned off. Example use cases: downloading a file or playing audio.
    • prevent-display-sleep - Prevent the display from going to sleep. Keeps system and screen active. Example use case: playing video.

Returns Integer - The blocker ID that is assigned to this power blocker.

Starts preventing the system from entering lower-power mode. Returns an integer identifying the power save blocker.

Note: prevent-display-sleep has higher precedence over prevent-app-suspension. Only the highest precedence type takes effect. In other words, prevent-display-sleep always takes precedence over prevent-app-suspension.

For example, an API calling A requests for prevent-app-suspension, and another calling B requests for prevent-display-sleep. prevent-display-sleep will be used until B stops its request. After that, prevent-app-suspension is used.

powerSaveBlocker.stop(id)

  • id Integer - The power save blocker id returned by powerSaveBlocker.start.

Stops the specified power save blocker.

powerSaveBlocker.isStarted(id)

  • id Integer - The power save blocker id returned by powerSaveBlocker.start.

Returns Boolean - Whether the corresponding powerSaveBlocker has started.


PrinterInfo Object

  • name String
  • description String
  • status Number
  • isDefault Boolean

Example

Below is an example of some of the additional options that may be set which may be different on each platform.

{
  name: 'Zebra_LP2844',
  description: 'Zebra LP2844',
  status: 3,
  isDefault: false,
  options: {
    copies: '1',
    'device-uri': 'usb://Zebra/LP2844?location=14200000',
    finishings: '3',
    'job-cancel-after': '10800',
    'job-hold-until': 'no-hold',
    'job-priority': '50',
    'job-sheets': 'none,none',
    'marker-change-time': '0',
    'number-up': '1',
    'printer-commands': 'none',
    'printer-info': 'Zebra LP2844',
    'printer-is-accepting-jobs': 'true',
    'printer-is-shared': 'true',
    'printer-location': '',
    'printer-make-and-model': 'Zebra EPL2 Label Printer',
    'printer-state': '3',
    'printer-state-change-time': '1484872644',
    'printer-state-reasons': 'offline-report',
    'printer-type': '36932',
    'printer-uri-supported': 'ipp://localhost/printers/Zebra_LP2844',
    system_driverinfo: 'Z'
  }
}

process

Extensions to process object.

Process: Main, Renderer

Electron's process object is extended from the Node.js process object. It adds the following events, properties, and methods:

Sandbox

In sandboxed renderers the process object contains only a subset of the APIs:

  • crash()
  • hang()
  • getHeapStatistics()
  • getProcessMemoryInfo()
  • getSystemMemoryInfo()
  • argv
  • execPath
  • env
  • platform

Event: 'loaded'

Emitted when Electron has loaded its internal initialization script and is beginning to load the web page or the main script.

It can be used by the preload script to add removed Node global symbols back to the global scope when node integration is turned off:

// preload.js
const _setImmediate = setImmediate
const _clearImmediate = clearImmediate
process.once('loaded', () => {
  global.setImmediate = _setImmediate
  global.clearImmediate = _clearImmediate
})

process.defaultApp

A Boolean. When app is started by being passed as parameter to the default app, this property is true in the main process, otherwise it is undefined.

process.mas

A Boolean. For Mac App Store build, this property is true, for other builds it is undefined.

process.noAsar

A Boolean that controls ASAR support inside your application. Setting this to true will disable the support for asar archives in Node's built-in modules.

process.noDeprecation

A Boolean that controls whether or not deprecation warnings are printed to stderr. Setting this to true will silence deprecation warnings. This property is used instead of the --no-deprecation command line flag.

process.resourcesPath

A String representing the path to the resources directory.

process.throwDeprecation

A Boolean that controls whether or not deprecation warnings will be thrown as exceptions. Setting this to true will throw errors for deprecations. This property is used instead of the --throw-deprecation command line flag.

process.traceDeprecation

A Boolean that controls whether or not deprecations printed to stderr include their stack trace. Setting this to true will print stack traces for deprecations. This property is instead of the --trace-deprecation command line flag.

process.traceProcessWarnings

A Boolean that controls whether or not process warnings printed to stderr include their stack trace. Setting this to true will print stack traces for process warnings (including deprecations). This property is instead of the --trace-warnings command line flag.

process.type

A String representing the current process's type, can be "browser" (i.e. main process) or "renderer".

process.versions.chrome

A String representing Chrome's version string.

process.versions.electron

A String representing Electron's version string.

process.windowsStore

A Boolean. If the app is running as a Windows Store app (appx), this property is true, for otherwise it is undefined.

Methods

The process object has the following methods:

process.crash()

Causes the main thread of the current process crash.

process.getHeapStatistics()

Returns Object:

  • totalHeapSize Integer
  • totalHeapSizeExecutable Integer
  • totalPhysicalSize Integer
  • totalAvailableSize Integer
  • usedHeapSize Integer
  • heapSizeLimit Integer
  • mallocedMemory Integer
  • peakMallocedMemory Integer
  • doesZapGarbage Boolean

Returns an object with V8 heap statistics. Note that all statistics are reported in Kilobytes.

process.getProcessMemoryInfo()

Returns Object:

  • workingSetSize Integer - The amount of memory currently pinned to actual physical RAM.
  • peakWorkingSetSize Integer - The maximum amount of memory that has ever been pinned to actual physical RAM.
  • privateBytes Integer - The amount of memory not shared by other processes, such as JS heap or HTML content.
  • sharedBytes Integer - The amount of memory shared between processes, typically memory consumed by the Electron code itself.

Returns an object giving memory usage statistics about the current process. Note that all statistics are reported in Kilobytes.

process.getSystemMemoryInfo()

Returns Object:

  • total Integer - The total amount of physical memory in Kilobytes available to the system.
  • free Integer - The total amount of memory not being used by applications or disk cache.
  • swapTotal Integer Windows Linux - The total amount of swap memory in Kilobytes available to the system.
  • swapFree Integer Windows Linux - The free amount of swap memory in Kilobytes available to the system.

Returns an object giving memory usage statistics about the entire system. Note that all statistics are reported in Kilobytes.

process.hang()

Causes the main thread of the current process hang.

process.setFdLimit(maxDescriptors) macOS Linux

  • maxDescriptors Integer

Sets the file descriptor soft limit to maxDescriptors or the OS hard limit, whichever is lower for the current process.


ProcessMetric Object

  • pid Integer - Process id of the process.
  • type String - Process type (Browser or Tab or GPU etc).
  • memory MemoryInfo - Memory information for the process.
  • cpu CPUUsage - CPU usage of the process.

Product Object

  • productIdentifier String - The string that identifies the product to the Apple App Store.
  • localizedDescription String - A description of the product.
  • localizedTitle String - The name of the product.
  • contentVersion String - A string that identifies the version of the content.
  • contentLengths Number[] - The total size of the content, in bytes.
  • price Number - The cost of the product in the local currency.
  • formattedPrice String - The locale formatted price of the product.
  • downloadable Boolean - A Boolean value that indicates whether the App Store has downloadable content for this product.

Progress Bar in Taskbar (Windows, macOS, Unity)

On Windows a taskbar button can be used to display a progress bar. This enables a window to provide progress information to the user without the user having to switch to the window itself.

On macOS the progress bar will be displayed as a part of the dock icon.

The Unity DE also has a similar feature that allows you to specify the progress bar in the launcher.

Progress bar in taskbar button:

Taskbar Progress Bar

All three cases are covered by the same API - the setProgressBar() method available on instances of BrowserWindows. Call it with a number between 0 and 1 to indicate your progress. If you have a long-running task that's currently at 63% towards completion, you'd call it with setProgressBar(0.63).

Generally speaking, setting the parameter to a value below zero (like -1) will remove the progress bar while setting it to a value higher than one (like 2) will switch the progress bar to intermediate mode.

See the API documentation for more options and modes.

const { BrowserWindow } = require('electron')
const win = new BrowserWindow()

win.setProgressBar(0.5)

protocol

Register a custom protocol and intercept existing protocol requests.

Process: Main

An example of implementing a protocol that has the same effect as the file:// protocol:

const {app, protocol} = require('electron')
const path = require('path')

app.on('ready', () => {
  protocol.registerFileProtocol('atom', (request, callback) => {
    const url = request.url.substr(7)
    callback({path: path.normalize(`${__dirname}/${url}`)})
  }, (error) => {
    if (error) console.error('Failed to register protocol')
  })
})

Note: All methods unless specified can only be used after the ready event of the app module gets emitted.

Methods

The protocol module has the following methods:

protocol.registerStandardSchemes(schemes[, options])

  • schemes String[] - Custom schemes to be registered as standard schemes.
  • options Object (optional)

    • secure Boolean (optional) - true to register the scheme as secure. Default false.

A standard scheme adheres to what RFC 3986 calls generic URI syntax. For example http and https are standard schemes, while file is not.

Registering a scheme as standard, will allow relative and absolute resources to be resolved correctly when served. Otherwise the scheme will behave like the file protocol, but without the ability to resolve relative URLs.

For example when you load following page with custom protocol without registering it as standard scheme, the image will not be loaded because non-standard schemes can not recognize relative URLs:

<body>
  <img src='test.png'>
</body>

Registering a scheme as standard will allow access to files through the FileSystem API. Otherwise the renderer will throw a security error for the scheme.

By default web storage apis (localStorage, sessionStorage, webSQL, indexedDB, cookies) are disabled for non standard schemes. So in general if you want to register a custom protocol to replace the http protocol, you have to register it as a standard scheme:

const {app, protocol} = require('electron')

protocol.registerStandardSchemes(['atom'])
app.on('ready', () => {
  protocol.registerHttpProtocol('atom', '...')
})

Note: This method can only be used before the ready event of the app module gets emitted.

protocol.registerServiceWorkerSchemes(schemes)

  • schemes String[] - Custom schemes to be registered to handle service workers.

protocol.registerFileProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • filePath String (optional)
  • completion Function (optional)

    • error Error

Registers a protocol of scheme that will send the file as a response. The handler will be called with handler(request, callback) when a request is going to be created with scheme. completion will be called with completion(null) when scheme is successfully registered or completion(error) when failed.

To handle the request, the callback should be called with either the file's path or an object that has a path property, e.g. callback(filePath) or callback({path: filePath}).

When callback is called with nothing, a number, or an object that has an error property, the request will fail with the error number you specified. For the available error numbers you can use, please see the net error list.

By default the scheme is treated like http:, which is parsed differently than protocols that follow the "generic URI syntax" like file:, so you probably want to call protocol.registerStandardSchemes to have your scheme treated as a standard scheme.

protocol.registerBufferProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

  • completion Function (optional)

    • error Error

Registers a protocol of scheme that will send a Buffer as a response.

The usage is the same with registerFileProtocol, except that the callback should be called with either a Buffer object or an object that has the data, mimeType, and charset properties.

Example:

const {protocol} = require('electron')

protocol.registerBufferProtocol('atom', (request, callback) => {
  callback({mimeType: 'text/html', data: Buffer.from('<h5>Response</h5>')})
}, (error) => {
  if (error) console.error('Failed to register protocol')
})

protocol.registerStringProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • data String (optional)
  • completion Function (optional)

    • error Error

Registers a protocol of scheme that will send a String as a response.

The usage is the same with registerFileProtocol, except that the callback should be called with either a String or an object that has the data, mimeType, and charset properties.

protocol.registerHttpProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • redirectRequest Object

        • url String
        • method String
        • session Object (optional)
        • uploadData Object (optional)

          • contentType String - MIME type of the content.
          • data String - Content to be sent.
  • completion Function (optional)

    • error Error

Registers a protocol of scheme that will send an HTTP request as a response.

The usage is the same with registerFileProtocol, except that the callback should be called with a redirectRequest object that has the url, method, referrer, uploadData and session properties.

By default the HTTP request will reuse the current session. If you want the request to have a different session you should set session to null.

For POST requests the uploadData object must be provided.

protocol.registerStreamProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • headers Object
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

  • completion Function (optional)

    • error Error

Registers a protocol of scheme that will send a Readable as a response.

The usage is similar to the other register{Any}Protocol, except that the callback should be called with either a Readable object or an object that has the data, statusCode, and headers properties.

Example:

const {protocol} = require('electron')
const {PassThrough} = require('stream')

function createStream (text) {
  const rv = new PassThrough() // PassThrough is also a Readable stream
  rv.push(text)
  rv.push(null)
  return rv
}

protocol.registerStreamProtocol('atom', (request, callback) => {
  callback({
    statusCode: 200,
    headers: {
      'content-type': 'text/html'
    },
    data: createStream('<h5>Response</h5>')
  })
}, (error) => {
  if (error) console.error('Failed to register protocol')
})

It is possible to pass any object that implements the readable stream API (emits data/end/error events). For example, here's how a file could be returned:

const {protocol} = require('electron')
const fs = require('fs')

protocol.registerStreamProtocol('atom', (request, callback) => {
  callback(fs.createReadStream('index.html'))
}, (error) => {
  if (error) console.error('Failed to register protocol')
})

protocol.unregisterProtocol(scheme[, completion])

  • scheme String
  • completion Function (optional)

    • error Error

Unregisters the custom protocol of scheme.

protocol.isProtocolHandled(scheme, callback)

  • scheme String
  • callback Function

    • error Error

The callback will be called with a boolean that indicates whether there is already a handler for scheme.

protocol.interceptFileProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • filePath String
  • completion Function (optional)

    • error Error

Intercepts scheme protocol and uses handler as the protocol's new handler which sends a file as a response.

protocol.interceptStringProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • data String (optional)
  • completion Function (optional)

    • error Error

Intercepts scheme protocol and uses handler as the protocol's new handler which sends a String as a response.

protocol.interceptBufferProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • buffer Buffer (optional)
  • completion Function (optional)

    • error Error

Intercepts scheme protocol and uses handler as the protocol's new handler which sends a Buffer as a response.

protocol.interceptHttpProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

      • redirectRequest Object

        • url String
        • method String
        • session Object (optional)
        • uploadData Object (optional)

          • contentType String - MIME type of the content.
          • data String - Content to be sent.
  • completion Function (optional)

    • error Error

Intercepts scheme protocol and uses handler as the protocol's new handler which sends a new HTTP request as a response.

protocol.interceptStreamProtocol(scheme, handler[, completion])

  • scheme String
  • handler Function

    • request Object

      • url String
      • headers Object
      • referrer String
      • method String
      • uploadData UploadData[]
    • callback Function

  • completion Function (optional)

    • error Error

Same as protocol.registerStreamProtocol, except that it replaces an existing protocol handler.

protocol.uninterceptProtocol(scheme[, completion])

  • scheme String
  • completion Function (optional)

    • error Error

Remove the interceptor installed for scheme and restore its original handler.


Step 1: Fork

Fork the project on GitHub and clone your fork locally.

$ git clone git@github.com:username/electron.git
$ cd electron
$ git remote add upstream https://github.com/electron/electron.git
$ git fetch upstream

Step 2: Build

Build steps and dependencies differ slightly depending on your operating system. See these detailed guides on building Electron locally:

Once you've built the project locally, you're ready to start making changes!

Step 3: Branch

To keep your development environment organized, create local branches to hold your work. These should be branched directly off of the master branch.

$ git checkout -b my-branch -t upstream/master

Step 4: Code

Most pull requests opened against the electron/electron repository include changes to either the C/C++ code in the atom/ folder, the JavaScript code in the lib/ folder, the documentation in docs/api/ or tests in the spec/ folder.

Please be sure to run npm run lint from time to time on any code changes to ensure that they follow the project's code style.

See coding style for more information about best practice when modifying code in different parts of the project.

Step 5: Commit

It is recommended to keep your changes grouped logically within individual commits. Many contributors find it easier to review changes that are split across multiple commits. There is no limit to the number of commits in a pull request.

$ git add my/changed/files
$ git commit

Note that multiple commits often get squashed when they are landed.

Commit message guidelines

A good commit message should describe what changed and why. The Electron project uses semantic commit messages to streamline the release process.

Before a pull request can be merged, it must have a pull request title with a semantic prefix.

Examples of commit messages with semantic prefixes:

  • fix: don't overwrite prevent_default if default wasn't prevented
  • feat: add app.isPackaged() method
  • docs: app.isDefaultProtocolClient is now available on Linux

Common prefixes:

  • fix: A bug fix
  • feat: A new feature
  • docs: Documentation changes
  • test: Adding missing tests or correcting existing tests
  • build: Changes that affect the build system
  • ci: Changes to our CI configuration files and scripts
  • perf: A code change that improves performance
  • refactor: A code change that neither fixes a bug nor adds a feature
  • style: Changes that do not affect the meaning of the code (linting)
  • vendor: Bumping a dependency like libchromiumcontent or node

Other things to keep in mind when writing a commit message:

  1. The first line should:

    • contain a short description of the change (preferably 50 characters or less, and no more than 72 characters)
    • be entirely in lowercase with the exception of proper nouns, acronyms, and the words that refer to code, like function/variable names
  2. Keep the second line blank.
  3. Wrap all other lines at 72 columns.

Breaking Changes

A commit that has the text BREAKING CHANGE: at the beginning of its optional body or footer section introduces a breaking API change (correlating with Major in semantic versioning). A breaking change can be part of commits of any type. e.g., a fix:, feat: & chore: types would all be valid, in addition to any other type.

See conventionalcommits.org for more details.

Step 6: Rebase

Once you have committed your changes, it is a good idea to use git rebase (not git merge) to synchronize your work with the main repository.

$ git fetch upstream
$ git rebase upstream/master

This ensures that your working branch has the latest changes from electron/electron master.

Step 7: Test

Bug fixes and features should always come with tests. A testing guide has been provided to make the process easier. Looking at other tests to see how they should be structured can also help.

Before submitting your changes in a pull request, always run the full test suite. To run the tests:

$ npm run test

Make sure the linter does not report any issues and that all tests pass. Please do not submit patches that fail either check.

If you are updating tests and want to run a single spec to check it:

$ npm run test -match=menu

The above would only run spec modules matching menu, which is useful for anyone who's working on tests that would otherwise be at the very end of the testing cycle.

Step 8: Push

Once your commits are ready to go -- with passing tests and linting -- begin the process of opening a pull request by pushing your working branch to your fork on GitHub.

$ git push origin my-branch

Step 9: Opening the Pull Request

From within GitHub, opening a new pull request will present you with a template that should be filled out:

<!--
Thank you for your pull request. Please provide a description above and review
the requirements below.

Bug fixes and new features should include tests and possibly benchmarks.

Contributors guide: https://github.com/electron/electron/blob/master/CONTRIBUTING.md
-->

Step 10: Discuss and update

You will probably get feedback or requests for changes to your pull request. This is a big part of the submission process so don't be discouraged! Some contributors may sign off on the pull request right away. Others may have detailed comments or feedback. This is a necessary part of the process in order to evaluate whether the changes are correct and necessary.

To make changes to an existing pull request, make the changes to your local branch, add a new commit with those changes, and push those to your fork. GitHub will automatically update the pull request.

$ git add my/changed/files
$ git commit
$ git push origin my-branch

There are a number of more advanced mechanisms for managing commits using git rebase that can be used, but are beyond the scope of this guide.

Feel free to post a comment in the pull request to ping reviewers if you are awaiting an answer on something. If you encounter words or acronyms that seem unfamiliar, refer to this glossary.

Approval and Request Changes Workflow

All pull requests require approval from a Code Owner of the area you modified in order to land. Whenever a maintainer reviews a pull request they may request changes. These may be small, such as fixing a typo, or may involve substantive changes. Such requests are intended to be helpful, but at times may come across as abrupt or unhelpful, especially if they do not include concrete suggestions on how to change them.

Try not to be discouraged. If you feel that a review is unfair, say so or seek the input of another project contributor. Often such comments are the result of a reviewer having taken insufficient time to review and are not ill-intended. Such difficulties can often be resolved with a bit of patience. That said, reviewers should be expected to provide helpful feeback.

Step 11: Landing

In order to land, a pull request needs to be reviewed and approved by at least one Electron Code Owner and pass CI. After that, if there are no objections from other contributors, the pull request can be merged.

Congratulations and thanks for your contribution!

Continuous Integration Testing

Every pull request is tested on the Continuous Integration (CI) system to confirm that it works on Electron's supported platforms.

Ideally, the pull request will pass ("be green") on all of CI's platforms. This means that all tests pass and there are no linting errors. However, it is not uncommon for the CI infrastructure itself to fail on specific platforms or for so-called "flaky" tests to fail ("be red"). Each CI failure must be manually inspected to determine the cause.

CI starts automatically when you open a pull request, but only Releasers can restart a CI run. If you believe CI is giving a false negative, ask a Releaser to restart the tests.


Quick Start

Electron enables you to create desktop applications with pure JavaScript by providing a runtime with rich native (operating system) APIs. You could see it as a variant of the Node.js runtime that is focused on desktop applications instead of web servers.

The old "Quick Start" document that used to live here has been split up into two documents:

To learn more about Electron, check out the official guides.


Official Guides

Please make sure that you use the documents that match your Electron version. The version number should be a part of the page URL. If it's not, you are probably using the documentation of a development branch which may contain API changes that are not compatible with your Electron version. To view older versions of the documentation, you can browse by tag on GitHub by opening the "Switch branches/tags" dropdown and selecting the tag that matches your version.

FAQ

There are questions that are asked quite often. Check this out before creating an issue:



Recent Documents (Windows & macOS)

Windows and macOS provide access to a list of recent documents opened by the application via JumpList or dock menu, respectively.

JumpList:

JumpList Recent Files

Application dock menu:

macOS Dock Menu

To add a file to recent documents, you can use the app.addRecentDocument API:

const { app } = require('electron')
app.addRecentDocument('/Users/USERNAME/Desktop/work.type')

And you can use app.clearRecentDocuments API to empty the recent documents list:

const { app } = require('electron')
app.clearRecentDocuments()

Windows Notes

In order to be able to use this feature on Windows, your application has to be registered as a handler of the file type of the document, otherwise the file won't appear in JumpList even after you have added it. You can find everything on registering your application in Application Registration.

When a user clicks a file from the JumpList, a new instance of your application will be started with the path of the file added as a command line argument.

macOS Notes

When a file is requested from the recent documents menu, the open-file event of app module will be emitted for it.


Rectangle Object

  • x Number - The x coordinate of the origin of the rectangle (must be an integer)
  • y Number - The y coordinate of the origin of the rectangle (must be an integer)
  • width Number - The width of the rectangle (must be an integer)
  • height Number - The height of the rectangle (must be an integer)

Referrer Object

  • url String - HTTP Referrer URL.
  • policy String - Can be default, unsafe-url, no-referrer-when-downgrade, no-referrer, origin, strict-origin-when-cross-origin, same-origin or strict-origin. See the Referrer-Policy spec for more details on the meaning of these values.

Releasing

This document describes the process for releasing a new version of Electron.

Set your tokens and environment variables

You'll need Electron S3 credentials in order to create and upload an Electron release. Contact a team member for more information.

There are a handful of *_TOKEN environment variables needed by the release scripts:

Once you've generated these tokens, put them in a .env file in the root directory of the project. This file is gitignored, and will be loaded into the environment by the release scripts.

Determine which branch to release from

  • If releasing beta, run the scripts below from master.
  • If releasing a stable version, run the scripts below from the branch you're stabilizing.

Find out what version change is needed

Run npm run prepare-release -- --notesOnly to view auto generated release notes. The notes generated should help you determine if this is a major, minor, patch, or beta version change. Read the Version Change Rules for more information.

NB: If releasing from a branch, e.g. 1-8-x, check out the branch with git checkout 1-8-x rather than git checkout -b remotes/origin/1-8-x. The scripts need git rev-parse --abbrev-ref HEAD to return a short name, e.g. no remotes/origin/

Run the prepare-release script

The prepare release script will do the following: 1. Check if a release is already in process and if so it will halt. 2. Create a release branch. 3. Bump the version number in several files. See this bump commit for an example. 4. Create a draft release on GitHub with auto-generated release notes. 5. Push the release branch. 6. Call the APIs to run the release builds.

Once you have determined which type of version change is needed, run the prepare-release script with arguments according to your need:

  • [major|minor|patch|beta] to increment one of the version numbers, or
  • --stable to indicate this is a stable version

For example:

Major version change

npm run prepare-release -- major

Minor version change

npm run prepare-release -- minor

Patch version change

npm run prepare-release -- patch --stable

Beta version change

npm run prepare-release -- beta

Promote beta to stable

npm run prepare-release -- --stable

Tip: You can test the new version number before running prepare-release with a dry run of the bump-version script with the same major/minor/patch/beta arguments, e.g.:

$ ./script/bump-version.py --bump minor --dry-run

Wait for builds ⏳

The prepare-release script will trigger the builds via API calls. To monitor the build progress, see the following pages:

Compile release notes

Writing release notes is a good way to keep yourself busy while the builds are running. For prior art, see existing releases on the releases page.

Tips:

  • Each listed item should reference a PR on electron/electron, not an issue, nor a PR from another repo like libcc.
  • No need to use link markup when referencing PRs. Strings like #123 will automatically be converted to links on github.com.
  • To see the version of Chromium, V8, and Node in every version of Electron, visit atom.io/download/electron/index.json.

Patch releases

For a patch release, use the following format:

## Bug Fixes

* Fixed a cross-platform thing. #123

### Linux

* Fixed a Linux thing. #123

### macOS

* Fixed a macOS thing. #123

### Windows

* Fixed a Windows thing. #1234

Minor releases

For a minor release, e.g. 1.8.0, use this format:

## Upgrades

- Upgraded from Node `oldVersion` to `newVersion`. #123

## API Changes

* Changed a thing. #123

### Linux

* Changed a Linux thing. #123

### macOS

* Changed a macOS thing. #123

### Windows

* Changed a Windows thing. #123

Major releases

## Upgrades

- Upgraded from Chromium `oldVersion` to `newVersion`. #123
- Upgraded from Node `oldVersion` to `newVersion`. #123

## Breaking API changes

* Changed a thing. #123

### Linux

* Changed a Linux thing. #123

### macOS

* Changed a macOS thing. #123

### Windows

* Changed a Windows thing. #123

## Other Changes

- Some other change. #123

Beta releases

Use the same formats as the ones suggested above, but add the following note at the beginning of the changelog:

**Note:** This is a beta release and most likely will have have some
instability and/or regressions.

Please file new issues for any bugs you find in it.

This release is published to [npm](https://www.npmjs.com/package/electron)
under the `beta` tag and can be installed via `npm install electron@beta`.

Edit the release draft

  1. Visit the releases page and you'll see a new draft release with placeholder release notes.
  2. Edit the release and add release notes.
  3. Click 'Save draft'. Do not click 'Publish release'!
  4. Wait for all builds to pass before proceeding.
  5. In the branch, verify that the release's files have been created:
$ npm run release -- --validateRelease

Note, if you need to run --validateRelease more than once to check the assets, run it as above the first time, then node ./script/release.js --validateRelease for subsequent calls so that you don't have to rebuild each time you want to check the assets.

Publish the release

Once the merge has finished successfully, run the release script via npm run release to finish the release process. This script will do the following: 1. Build the project to validate that the correct version number is being released. 2. Download the binaries and generate the node headers and the .lib linker used on Windows by node-gyp to build native modules. 3. Create and upload the SHASUMS files stored on S3 for the node files. 4. Create and upload the SHASUMS256.txt file stored on the GitHub release. 5. Validate that all of the required files are present on GitHub and S3 and have the correct checksums as specified in the SHASUMS files. 6. Publish the release on GitHub

Publish to npm

Before publishing to npm, you'll need to log into npm as Electron. Optionally, you may find npmrc to be a useful way to keep Electron's profile side-by-side with your own:

$ sudo npm install -g npmrc
$ npmrc -c electron
Removing old .npmrc (default)
Activating .npmrc "electron"

The Electron account's credentials are kept by GitHub in a password manager. You'll also need to have access to an 2FA authenticator app with the appropriate OTP generator code to log in.

$ npm login
Username: electron-nightly
Password: <This can be found under NPM Electron Nightly on LastPass>
Email: (this IS public) electron@github.com

Publish the release to npm. Before running this you'll need to have set ELECTRON_NPM_OTP as an environment variable using a code from the aforementioned 2FA authenticator app.

$ npm whoami
electron-nightly
$ npm run publish-to-npm

After publishing, you can check the latest release:

$ npm dist-tag ls electron

If for some reason npm run publish-to-npm fails, you can tag the release manually:

$ npm dist-tag add electron@<version> <tag>

e.g.:

$ npm dist-tag add electron@2.0.0 latest

Rerun broken builds

If a release build fails for some reason, you can use script/ci-release-build.js to rerun a release build:

Rerun all linux builds:

node script/ci-release-build.js --ci=CircleCI --ghRelease TARGET_BRANCH
(TARGET_BRANCH) is the branch you are releasing from.

Rerun all macOS builds:

node script/ci-release-build.js --ci=VSTS --ghRelease TARGET_BRANCH
(TARGET_BRANCH) is the branch you are releasing from.

Rerun all Windows builds:

node script/ci-release-build.js --ci=AppVeyor --ghRelease TARGET_BRANCH
(TARGET_BRANCH) is the branch you are releasing from.

Additionally you can pass a job name to the script to run an individual job, eg:

node script/ci-release-build.js --ci=AppVeyor --ghRelease --job=electron-x64 TARGET_BRANCH

Fix missing binaries of a release manually

In the case of a corrupted release with broken CI machines, we might have to re-upload the binaries for an already published release.

The first step is to go to the Releases page and delete the corrupted binaries with the SHASUMS256.txt checksum file.

Then manually create distributions for each platform and upload them:

# Checkout the version to re-upload.
git checkout vX.Y.Z

# Create release build
gn gen out/Release --args="import(\"//electron/build/args/release.gn\") $GN_EXTRA_ARGS"

# To compile for specific arch, instead set
gn gen out/Release-<TARGET_ARCH> --args='import(\"//electron/build/args/release.gn\") target_cpu = "[arm|x64|ia32]"'

# Build by running ninja with the electron target
ninja -C out/Release electron
ninja -C out/Release electron:dist_zip

# Explicitly allow overwriting a published release.
./script/upload.py --overwrite

Allowable values for target_cpu and target_os.

After re-uploading all distributions, publish again to upload the checksum file:

npm run release

remote

Use main process modules from the renderer process.

Process: Renderer

The remote module provides a simple way to do inter-process communication (IPC) between the renderer process (web page) and the main process.

In Electron, GUI-related modules (such as dialog, menu etc.) are only available in the main process, not in the renderer process. In order to use them from the renderer process, the ipc module is necessary to send inter-process messages to the main process. With the remote module, you can invoke methods of the main process object without explicitly sending inter-process messages, similar to Java's RMI. An example of creating a browser window from a renderer process:

const {BrowserWindow} = require('electron').remote
let win = new BrowserWindow({width: 800, height: 600})
win.loadURL('https://github.com')

Note: For the reverse (access the renderer process from the main process), you can use webContents.executeJavaScript.

Remote Objects

Each object (including functions) returned by the remote module represents an object in the main process (we call it a remote object or remote function). When you invoke methods of a remote object, call a remote function, or create a new object with the remote constructor (function), you are actually sending synchronous inter-process messages.

In the example above, both BrowserWindow and win were remote objects and new BrowserWindow didn't create a BrowserWindow object in the renderer process. Instead, it created a BrowserWindow object in the main process and returned the corresponding remote object in the renderer process, namely the win object.

Note: Only enumerable properties which are present when the remote object is first referenced are accessible via remote.

Note: Arrays and Buffers are copied over IPC when accessed via the remote module. Modifying them in the renderer process does not modify them in the main process and vice versa.

Lifetime of Remote Objects

Electron makes sure that as long as the remote object in the renderer process lives (in other words, has not been garbage collected), the corresponding object in the main process will not be released. When the remote object has been garbage collected, the corresponding object in the main process will be dereferenced.

If the remote object is leaked in the renderer process (e.g. stored in a map but never freed), the corresponding object in the main process will also be leaked, so you should be very careful not to leak remote objects.

Primary value types like strings and numbers, however, are sent by copy.

Passing callbacks to the main process

Code in the main process can accept callbacks from the renderer - for instance the remote module - but you should be extremely careful when using this feature.

First, in order to avoid deadlocks, the callbacks passed to the main process are called asynchronously. You should not expect the main process to get the return value of the passed callbacks.

For instance you can't use a function from the renderer process in an Array.map called in the main process:

// main process mapNumbers.js
exports.withRendererCallback = (mapper) => {
  return [1, 2, 3].map(mapper)
}

exports.withLocalCallback = () => {
  return [1, 2, 3].map(x => x + 1)
}
// renderer process
const mapNumbers = require('electron').remote.require('./mapNumbers')
const withRendererCb = mapNumbers.withRendererCallback(x => x + 1)
const withLocalCb = mapNumbers.withLocalCallback()

console.log(withRendererCb, withLocalCb)
// [undefined, undefined, undefined], [2, 3, 4]

As you can see, the renderer callback's synchronous return value was not as expected, and didn't match the return value of an identical callback that lives in the main process.

Second, the callbacks passed to the main process will persist until the main process garbage-collects them.

For example, the following code seems innocent at first glance. It installs a callback for the close event on a remote object:

require('electron').remote.getCurrentWindow().on('close', () => {
  // window was closed...
})

But remember the callback is referenced by the main process until you explicitly uninstall it. If you do not, each time you reload your window the callback will be installed again, leaking one callback for each restart.

To make things worse, since the context of previously installed callbacks has been released, exceptions will be raised in the main process when the close event is emitted.

To avoid this problem, ensure you clean up any references to renderer callbacks passed to the main process. This involves cleaning up event handlers, or ensuring the main process is explicitly told to dereference callbacks that came from a renderer process that is exiting.

Accessing built-in modules in the main process

The built-in modules in the main process are added as getters in the remote module, so you can use them directly like the electron module.

const app = require('electron').remote.app
console.log(app)

Methods

The remote module has the following methods:

remote.require(module)

  • module String

Returns any - The object returned by require(module) in the main process. Modules specified by their relative path will resolve relative to the entrypoint of the main process.

e.g.

project/
├── main
│   ├── foo.js
│   └── index.js
├── package.json
└── renderer
    └── index.js
// main process: main/index.js
const {app} = require('electron')
app.on('ready', () => { /* ... */ })
// some relative module: main/foo.js
module.exports = 'bar'
// renderer process: renderer/index.js
const foo = require('electron').remote.require('./foo') // bar

remote.getCurrentWindow()

Returns BrowserWindow - The window to which this web page belongs.

Note: Do not use removeAllListeners on BrowserWindow. Use of this can remove all blur listeners, disable click events on touch bar buttons, and other unintended consequences.

remote.getCurrentWebContents()

Returns WebContents - The web contents of this web page.

remote.getGlobal(name)

  • name String

Returns any - The global variable of name (e.g. global[name]) in the main process.

remote.process

The process object in the main process. This is the same as remote.getGlobal('process') but is cached.


RemoveClientCertificate Object

  • type String - clientCertificate.
  • origin String - Origin of the server whose associated client certificate must be removed from the cache.

RemovePassword Object

  • type String - password.
  • origin String (optional) - When provided, the authentication info related to the origin will only be removed otherwise the entire cache will be cleared.
  • scheme String (optional) - Scheme of the authentication. Can be basic, digest, ntlm, negotiate. Must be provided if removing by origin.
  • realm String (optional) - Realm of the authentication. Must be provided if removing by origin.
  • username String (optional) - Credentials of the authentication. Must be provided if removing by origin.
  • password String (optional) - Credentials of the authentication. Must be provided if removing by origin.

REPL

Read-Eval-Print-Loop (REPL) is a simple, interactive computer programming environment that takes single user inputs (i.e. single expressions), evaluates them, and returns the result to the user.

The repl module provides a REPL implementation that can be accessed using:

  • Assuming you have electron or electron-prebuilt installed as a local project dependency:

    ./node_modules/.bin/electron --interactive
  • Assuming you have electron or electron-prebuilt installed globally:

    electron --interactive

This only creates a REPL for the main process. You can use the Console tab of the Dev Tools to get a REPL for the renderer processes.

Note: electron --interactive is not available on Windows.

More information can be found in the Node.js REPL docs.


Represented File for macOS BrowserWindows

On macOS a window can set its represented file, so the file's icon can show in the title bar and when users Command-Click or Control-Click on the title a path popup will show.

You can also set the edited state of a window so that the file icon can indicate whether the document in this window has been modified.

Represented file popup menu:

Represented File

To set the represented file of window, you can use the BrowserWindow.setRepresentedFilename and BrowserWindow.setDocumentEdited APIs:

const { BrowserWindow } = require('electron')

const win = new BrowserWindow()
win.setRepresentedFilename('/etc/passwd')
win.setDocumentEdited(true)

sandbox Option

Create a browser window with a renderer that can run inside Chromium OS sandbox. With this option enabled, the renderer must communicate via IPC to the main process in order to access node APIs. However, in order to enable the Chromium OS sandbox, electron must be run with the --enable-sandbox command line argument.

One of the key security features of Chromium is that all blink rendering/JavaScript code is executed within a sandbox. This sandbox uses OS-specific features to ensure that exploits in the renderer process cannot harm the system.

In other words, when the sandbox is enabled, the renderers can only make changes to the system by delegating tasks to the main process via IPC. Here's more information about the sandbox.

Since a major feature in electron is the ability to run node.js in the renderer process (making it easier to develop desktop applications using web technologies), the sandbox is disabled by electron. This is because most node.js APIs require system access. require() for example, is not possible without file system permissions, which are not available in a sandboxed environment.

Usually this is not a problem for desktop applications since the code is always trusted, but it makes electron less secure than chromium for displaying untrusted web content. For applications that require more security, the sandbox flag will force electron to spawn a classic chromium renderer that is compatible with the sandbox.

A sandboxed renderer doesn't have a node.js environment running and doesn't expose node.js JavaScript APIs to client code. The only exception is the preload script, which has access to a subset of the electron renderer API.

Another difference is that sandboxed renderers don't modify any of the default JavaScript APIs. Consequently, some APIs such as window.open will work as they do in chromium (i.e. they do not return a BrowserWindowProxy).

Example

To create a sandboxed window, pass sandbox: true to webPreferences:

let win
app.on('ready', () => {
  win = new BrowserWindow({
    webPreferences: {
      sandbox: true
    }
  })
  win.loadURL('http://google.com')
})

In the above code the BrowserWindow that was created has node.js disabled and can communicate only via IPC. The use of this option stops electron from creating a node.js runtime in the renderer. Also, within this new window window.open follows the native behaviour (by default electron creates a BrowserWindow and returns a proxy to this via window.open).

It is important to note that this option alone won't enable the OS-enforced sandbox. To enable this feature, the --enable-sandbox command-line argument must be passed to electron, which will force sandbox: true for all BrowserWindow instances.

To enable OS-enforced sandbox on BrowserWindow or webview process with sandbox:true without causing entire app to be in sandbox, --enable-mixed-sandbox command-line argument must be passed to electron. This option is currently only supported on macOS and Windows.

let win
app.on('ready', () => {
  // no need to pass `sandbox: true` since `--enable-sandbox` was enabled.
  win = new BrowserWindow()
  win.loadURL('http://google.com')
})

Note that it is not enough to call app.commandLine.appendSwitch('--enable-sandbox'), as electron/node startup code runs after it is possible to make changes to chromium sandbox settings. The switch must be passed to electron on the command-line:

electron --enable-sandbox app.js

It is not possible to have the OS sandbox active only for some renderers, if --enable-sandbox is enabled, normal electron windows cannot be created.

If you need to mix sandboxed and non-sandboxed renderers in one application, omit the --enable-sandbox argument. Without this argument, windows created with sandbox: true will still have node.js disabled and communicate only via IPC, which by itself is already a gain from security POV.

Preload

An app can make customizations to sandboxed renderers using a preload script. Here's an example:

let win
app.on('ready', () => {
  win = new BrowserWindow({
    webPreferences: {
      sandbox: true,
      preload: 'preload.js'
    }
  })
  win.loadURL('http://google.com')
})

and preload.js:

// This file is loaded whenever a javascript context is created. It runs in a
// private scope that can access a subset of electron renderer APIs. We must be
// careful to not leak any objects into the global scope!
const fs = require('fs')
const {ipcRenderer} = require('electron')

// read a configuration file using the `fs` module
const buf = fs.readFileSync('allowed-popup-urls.json')
const allowedUrls = JSON.parse(buf.toString('utf8'))

const defaultWindowOpen = window.open

function customWindowOpen (url, ...args) {
  if (allowedUrls.indexOf(url) === -1) {
    ipcRenderer.sendSync('blocked-popup-notification', location.origin, url)
    return null
  }
  return defaultWindowOpen(url, ...args)
}

window.open = customWindowOpen

Important things to notice in the preload script:

  • Even though the sandboxed renderer doesn't have node.js running, it still has access to a limited node-like environment: Buffer, process, setImmediate and require are available.
  • The preload script can indirectly access all APIs from the main process through the remote and ipcRenderer modules. This is how fs (used above) and other modules are implemented: They are proxies to remote counterparts in the main process.
  • The preload script must be contained in a single script, but it is possible to have complex preload code composed with multiple modules by using a tool like browserify, as explained below. In fact, browserify is already used by electron to provide a node-like environment to the preload script.

To create a browserify bundle and use it as a preload script, something like the following should be used:

  browserify preload/index.js \
    -x electron \
    -x fs \
    --insert-global-vars=__filename,__dirname -o preload.js

The -x flag should be used with any required module that is already exposed in the preload scope, and tells browserify to use the enclosing require function for it. --insert-global-vars will ensure that process, Buffer and setImmediate are also taken from the enclosing scope(normally browserify injects code for those).

Currently the require function provided in the preload scope exposes the following modules:

  • child_process
  • electron

    • crashReporter
    • remote
    • ipcRenderer
    • webFrame
  • fs
  • os
  • timers
  • url

More may be added as needed to expose more electron APIs in the sandbox, but any module in the main process can already be used through electron.remote.require.

Status

Please use the sandbox option with care, as it is still an experimental feature. We are still not aware of the security implications of exposing some electron renderer APIs to the preload script, but here are some things to consider before rendering untrusted content:

  • A preload script can accidentally leak privileged APIs to untrusted code.
  • Some bug in V8 engine may allow malicious code to access the renderer preload APIs, effectively granting full access to the system through the remote module.

Since rendering untrusted content in electron is still uncharted territory, the APIs exposed to the sandbox preload script should be considered more unstable than the rest of electron APIs, and may have breaking changes to fix security issues.

One planned enhancement that should greatly increase security is to block IPC messages from sandboxed renderers by default, allowing the main process to explicitly define a set of messages the renderer is allowed to send.


screen

Retrieve information about screen size, displays, cursor position, etc.

Process: Main, Renderer

You cannot require or use this module until the ready event of the app module is emitted.

screen is an EventEmitter.

Note: In the renderer / DevTools, window.screen is a reserved DOM property, so writing let {screen} = require('electron') will not work.

An example of creating a window that fills the whole screen:

const electron = require('electron')
const {app, BrowserWindow} = electron

let win

app.on('ready', () => {
  const {width, height} = electron.screen.getPrimaryDisplay().workAreaSize
  win = new BrowserWindow({width, height})
  win.loadURL('https://github.com')
})

Another example of creating a window in the external display:

const electron = require('electron')
const {app, BrowserWindow} = require('electron')

let win

app.on('ready', () => {
  let displays = electron.screen.getAllDisplays()
  let externalDisplay = displays.find((display) => {
    return display.bounds.x !== 0 || display.bounds.y !== 0
  })

  if (externalDisplay) {
    win = new BrowserWindow({
      x: externalDisplay.bounds.x + 50,
      y: externalDisplay.bounds.y + 50
    })
    win.loadURL('https://github.com')
  }
})

Events

The screen module emits the following events:

Event: 'display-added'

Returns:

Emitted when newDisplay has been added.

Event: 'display-removed'

Returns:

Emitted when oldDisplay has been removed.

Event: 'display-metrics-changed'

Returns:

  • event Event
  • display Display
  • changedMetrics String[]

Emitted when one or more metrics change in a display. The changedMetrics is an array of strings that describe the changes. Possible changes are bounds, workArea, scaleFactor and rotation.

Methods

The screen module has the following methods:

screen.getCursorScreenPoint()

Returns Point

The current absolute position of the mouse pointer.

screen.getPrimaryDisplay()

Returns Display - The primary display.

screen.getAllDisplays()

Returns Display[] - An array of displays that are currently available.

screen.getDisplayNearestPoint(point)

Returns Display - The display nearest the specified point.

screen.getDisplayMatching(rect)

Returns Display - The display that most closely intersects the provided bounds.

screen.screenToDipPoint(point) Windows

Returns Point

Converts a screen physical point to a screen DIP point. The DPI scale is performed relative to the display containing the physical point.

screen.dipToScreenPoint(point) Windows

Returns Point

Converts a screen DIP point to a screen physical point. The DPI scale is performed relative to the display containing the DIP point.

screen.screenToDipRect(window, rect) Windows

Returns Rectangle

Converts a screen physical rect to a screen DIP rect. The DPI scale is performed relative to the display nearest to window. If window is null, scaling will be performed to the display nearest to rect.

screen.dipToScreenRect(window, rect) Windows

Returns Rectangle

Converts a screen DIP rect to a screen physical rect. The DPI scale is performed relative to the display nearest to window. If window is null, scaling will be performed to the display nearest to rect.


ScrubberItem Object

  • label String (optional) - The text to appear in this item
  • icon NativeImage (optional) - The image to appear in this item

Security, Native Capabilities, and Your Responsibility

As web developers, we usually enjoy the strong security net of the browser - the risks associated with the code we write are relatively small. Our websites are granted limited powers in a sandbox, and we trust that our users enjoy a browser built by a large team of engineers that is able to quickly respond to newly discovered security threats.

When working with Electron, it is important to understand that Electron is not a web browser. It allows you to build feature-rich desktop applications with familiar web technologies, but your code wields much greater power. JavaScript can access the filesystem, user shell, and more. This allows you to build high quality native applications, but the inherent security risks scale with the additional powers granted to your code.

With that in mind, be aware that displaying arbitrary content from untrusted sources poses a severe security risk that Electron is not intended to handle. In fact, the most popular Electron apps (Atom, Slack, Visual Studio Code, etc) display primarily local content (or trusted, secure remote content without Node integration) – if your application executes code from an online source, it is your responsibility to ensure that the code is not malicious.

Reporting Security Issues

For information on how to properly disclose an Electron vulnerability, see SECURITY.md

Chromium Security Issues and Upgrades

While Electron strives to support new versions of Chromium as soon as possible, developers should be aware that upgrading is a serious undertaking - involving hand-editing dozens or even hundreds of files. Given the resources and contributions available today, Electron will often not be on the very latest version of Chromium, lagging behind by several weeks or a few months.

We feel that our current system of updating the Chromium component strikes an appropriate balance between the resources we have available and the needs of the majority of applications built on top of the framework. We definitely are interested in hearing more about specific use cases from the people that build things on top of Electron. Pull requests and contributions supporting this effort are always very welcome.

Ignoring Above Advice

A security issue exists whenever you receive code from a remote destination and execute it locally. As an example, consider a remote website being displayed inside a BrowserWindow. If an attacker somehow manages to change said content (either by attacking the source directly, or by sitting between your app and the actual destination), they will be able to execute native code on the user's machine.

⚠️ Under no circumstances should you load and execute remote code with Node.js integration enabled. Instead, use only local files (packaged together with your application) to execute Node.js code. To display remote content, use the <webview> tag and make sure to disable the nodeIntegration.

Electron Security Warnings

From Electron 2.0 on, developers will see warnings and recommendations printed to the developer console. They only show up when the binary's name is Electron, indicating that a developer is currently looking at the console.

You can force-enable or force-disable these warnings by setting ELECTRON_ENABLE_SECURITY_WARNINGS or ELECTRON_DISABLE_SECURITY_WARNINGS on either process.env or the window object.

1) Only Load Secure Content

Any resources not included with your application should be loaded using a secure protocol like HTTPS. In other words, do not use insecure protocols like HTTP. Similarly, we recommend the use of WSS over WS, FTPS over FTP, and so on.

Why?

HTTPS has three main benefits:

1) It authenticates the remote server, ensuring your app connects to the correct host instead of an impersonator. 2) It ensures data integrity, asserting that the data was not modified while in transit between your application and the host. 3) It encrypts the traffic between your user and the destination host, making it more difficult to eavesdrop on the information sent between your app and the host.

How?

// Bad
browserWindow.loadURL('http://my-website.com')

// Good
browserWindow.loadURL('https://my-website.com')
<!-- Bad -->
<script crossorigin src="http://cdn.com/react.js"></script>
<link rel="stylesheet" href="http://cdn.com/style.css">

<!-- Good -->
<script crossorigin src="https://cdn.com/react.js"></script>
<link rel="stylesheet" href="https://cdn.com/style.css">

2) Disable Node.js Integration for Remote Content

It is paramount that you disable Node.js integration in any renderer (BrowserWindow, BrowserView, or <webview>) that loads remote content. The goal is to limit the powers you grant to remote content, thus making it dramatically more difficult for an attacker to harm your users should they gain the ability to execute JavaScript on your website.

After this, you can grant additional permissions for specific hosts. For example, if you are opening a BrowserWindow pointed at `https://my-website.com/", you can give that website exactly the abilities it needs, but no more.

Why?

A cross-site-scripting (XSS) attack is more dangerous if an attacker can jump out of the renderer process and execute code on the user's computer. Cross-site-scripting attacks are fairly common - and while an issue, their power is usually limited to messing with the website that they are executed on. Disabling Node.js integration helps prevent an XSS from being escalated into a so-called "Remote Code Execution" (RCE) attack.

How?

// Bad
const mainWindow = new BrowserWindow()
mainWindow.loadURL('https://my-website.com')
// Good
const mainWindow = new BrowserWindow({
  webPreferences: {
    nodeIntegration: false,
    preload: './preload.js'
  }
})

mainWindow.loadURL('https://my-website.com')
<!-- Bad -->
<webview nodeIntegration src="page.html"></webview>

<!-- Good -->
<webview src="page.html"></webview>

When disabling Node.js integration, you can still expose APIs to your website that do consume Node.js modules or features. Preload scripts continue to have access to require and other Node.js features, allowing developers to expose a custom API to remotely loaded content.

In the following example preload script, the later loaded website will have access to a window.readConfig() method, but no Node.js features.

const { readFileSync } = require('fs')

window.readConfig = function () {
  const data = readFileSync('./config.json')
  return data
}

3) Enable Context Isolation for Remote Content

Context isolation is an Electron feature that allows developers to run code in preload scripts and in Electron APIs in a dedicated JavaScript context. In practice, that means that global objects like Array.prototype.push or JSON.parse cannot be modified by scripts running in the renderer process.

Electron uses the same technology as Chromium's Content Scripts to enable this behavior.

Why?

Context isolation allows each the scripts on running in the renderer to make changes to its JavaScript environment without worrying about conflicting with the scripts in the Electron API or the preload script.

While still an experimental Electron feature, context isolation adds an additional layer of security. It creates a new JavaScript world for Electron APIs and preload scripts.

At the same time, preload scripts still have access to the document and window objects. In other words, you're getting a decent return on a likely very small investment.

How?

// Main process
const mainWindow = new BrowserWindow({
  webPreferences: {
    contextIsolation: true,
    preload: 'preload.js'
  }
})
// Preload script

// Set a variable in the page before it loads
webFrame.executeJavaScript('window.foo = "foo";')

// The loaded page will not be able to access this, it is only available
// in this context
window.bar = 'bar'

document.addEventListener('DOMContentLoaded', () => {
  // Will log out 'undefined' since window.foo is only available in the main
  // context
  console.log(window.foo)

  // Will log out 'bar' since window.bar is available in this context
  console.log(window.bar)
})

4) Handle Session Permission Requests From Remote Content

You may have seen permission requests while using Chrome: They pop up whenever the website attempts to use a feature that the user has to manually approve ( like notifications).

The API is based on the Chromium permissions API and implements the same types of permissions.

Why?

By default, Electron will automatically approve all permission requests unless the developer has manually configured a custom handler. While a solid default, security-conscious developers might want to assume the very opposite.

How?

const { session } = require('electron')

session
  .fromPartition('some-partition')
  .setPermissionRequestHandler((webContents, permission, callback) => {
    const url = webContents.getURL()

    if (permission === 'notifications') {
      // Approves the permissions request
      callback(true)
    }

    if (!url.startsWith('https://my-website.com')) {
      // Denies the permissions request
      return callback(false)
    }
  })

5) Do Not Disable WebSecurity

Recommendation is Electron's default

You may have already guessed that disabling the webSecurity property on a renderer process (BrowserWindow, BrowserView, or <webview>) disables crucial security features.

Do not disable webSecurity in production applications.

Why?

Disabling webSecurity will disable the same-origin policy and set allowRunningInsecureContent property to true. In other words, it allows the execution of insecure code from different domains.

How?

// Bad
const mainWindow = new BrowserWindow({
  webPreferences: {
    webSecurity: false
  }
})
// Good
const mainWindow = new BrowserWindow()
<!-- Bad -->
<webview disablewebsecurity src="page.html"></webview>

<!-- Good -->
<webview src="page.html"></webview>

6) Define a Content Security Policy

A Content Security Policy (CSP) is an additional layer of protection against cross-site-scripting attacks and data injection attacks. We recommend that they be enabled by any website you load inside Electron.

Why?

CSP allows the server serving content to restrict and control the resources Electron can load for that given web page. https://your-page.com should be allowed to load scripts from the origins you defined while scripts from https://evil.attacker.com should not be allowed to run. Defining a CSP is an easy way to improve your application's security.

The following CSP will allow Electron to execute scripts from the current website and from apis.mydomain.com.

// Bad
Content-Security-Policy: '*'

// Good
Content-Security-Policy: script-src 'self' https://apis.mydomain.com

CSP HTTP Header

Electron respects the Content-Security-Policy HTTP header which can be set using Electron's webRequest.onHeadersReceived handler:

const { session } = require('electron')

session.defaultSession.webRequest.onHeadersReceived((details, callback) => {
  callback({
    responseHeaders: {
      ...details.responseHeaders,
      'Content-Security-Policy': ['default-src \'none\'']
    }
  })
})

CSP Meta Tag

CSP's preferred delivery mechanism is an HTTP header, however it is not possible to use this method when loading a resource using the file:// protocol. It can be useful in some cases, such as using the file:// protocol, to set a policy on a page directly in the markup using a <meta> tag:

<meta http-equiv="Content-Security-Policy" content="default-src 'none'">

7) Do Not Set allowRunningInsecureContent to true

Recommendation is Electron's default

By default, Electron will not allow websites loaded over HTTPS to load and execute scripts, CSS, or plugins from insecure sources (HTTP). Setting the property allowRunningInsecureContent to true disables that protection.

Loading the initial HTML of a website over HTTPS and attempting to load subsequent resources via HTTP is also known as "mixed content".

Why?

Loading content over HTTPS assures the authenticity and integrity of the loaded resources while encrypting the traffic itself. See the section on only displaying secure content for more details.

How?

// Bad
const mainWindow = new BrowserWindow({
  webPreferences: {
    allowRunningInsecureContent: true
  }
})
// Good
const mainWindow = new BrowserWindow({})

8) Do Not Enable Experimental Features

Recommendation is Electron's default

Advanced users of Electron can enable experimental Chromium features using the experimentalFeatures property.

Why?

Experimental features are, as the name suggests, experimental and have not been enabled for all Chromium users. Furthermore, their impact on Electron as a whole has likely not been tested.

Legitimate use cases exist, but unless you know what you are doing, you should not enable this property.

How?

// Bad
const mainWindow = new BrowserWindow({
  webPreferences: {
    experimentalFeatures: true
  }
})
// Good
const mainWindow = new BrowserWindow({})

9) Do Not Use enableBlinkFeatures

Recommendation is Electron's default

Blink is the name of the rendering engine behind Chromium. As with experimentalFeatures, the enableBlinkFeatures property allows developers to enable features that have been disabled by default.

Why?

Generally speaking, there are likely good reasons if a feature was not enabled by default. Legitimate use cases for enabling specific features exist. As a developer, you should know exactly why you need to enable a feature, what the ramifications are, and how it impacts the security of your application. Under no circumstances should you enable features speculatively.

How?

// Bad
const mainWindow = new BrowserWindow({
  webPreferences: {
    enableBlinkFeatures: ['ExecCommandInJavaScript']
  }
})
// Good
const mainWindow = new BrowserWindow()

10) Do Not Use allowpopups

Recommendation is Electron's default

If you are using <webview>, you might need the pages and scripts loaded in your <webview> tag to open new windows. The allowpopups attribute enables them to create new BrowserWindows using the window.open() method. <webview> tags are otherwise not allowed to create new windows.

Why?

If you do not need popups, you are better off not allowing the creation of new BrowserWindows by default. This follows the principle of minimally required access: Don't let a website create new popups unless you know it needs that feature.

How?

<!-- Bad -->
<webview allowpopups src="page.html"></webview>

<!-- Good -->
<webview src="page.html"></webview>

11) Verify WebView Options Before Creation

A WebView created in a renderer process that does not have Node.js integration enabled will not be able to enable integration itself. However, a WebView will always create an independent renderer process with its own webPreferences.

It is a good idea to control the creation of new <webview> tags from the main process and to verify that their webPreferences do not disable security features.

Why?

Since <webview> live in the DOM, they can be created by a script running on your website even if Node.js integration is otherwise disabled.

Electron enables developers to disable various security features that control a renderer process. In most cases, developers do not need to disable any of those features - and you should therefore not allow different configurations for newly created <webview> tags.

How?

Before a <webview> tag is attached, Electron will fire the will-attach-webview event on the hosting webContents. Use the event to prevent the creation of webViews with possibly insecure options.

app.on('web-contents-created', (event, contents) => {
  contents.on('will-attach-webview', (event, webPreferences, params) => {
    // Strip away preload scripts if unused or verify their location is legitimate
    delete webPreferences.preload
    delete webPreferences.preloadURL

    // Disable Node.js integration
    webPreferences.nodeIntegration = false

    // Verify URL being loaded
    if (!params.src.startsWith('https://yourapp.com/')) {
      event.preventDefault()
    }
  })
})

Again, this list merely minimizes the risk, it does not remove it. If your goal is to display a website, a browser will be a more secure option.

12) Disable or limit navigation

If your app has no need to navigate or only needs to navigate to known pages, it is a good idea to limit navigation outright to that known scope, disallowing any other kinds of navigation.

Why?

Navigation is a common attack vector. If an attacker can convince your app to navigate away from its current page, they can possibly force your app to open web sites on the Internet. Even if your webContents are configured to be more secure (like having nodeIntegration disabled or contextIsolation enabled), getting your app to open a random web site will make the work of exploiting your app a lot easier.

A common attack pattern is that the attacker convinces your app's users to interact with the app in such a way that it navigates to one of the attacker's pages. This is usually done via links, plugins, or other user-generated content.

How?

If your app has no need for navigation, you can call event.preventDefault() in a will-navigate handler. If you know which pages your app might navigate to, check the URL in the event handler and only let navigation occur if it matches the URLs you're expecting.

We recommend that you use Node's parser for URLs. Simple string comparisons can sometimes be fooled - a startsWith('https://google.com') test would let https://google.com.attacker.com through.

const URL = require('url').URL

app.on('web-contents-created', (event, contents) => {
  contents.on('will-navigate', (event, navigationUrl) => {
    const parsedUrl = new URL(navigationUrl)

    if (parsedUrl.origin !== 'https://my-own-server.com') {
      event.preventDefault()
    }
  })
})

13) Disable or limit creation of new windows

If you have a known set of windows, it's a good idea to limit the creation of additional windows in your app.

Why?

Much like navigation, the creation of new webContents is a common attack vector. Attackers attempt to convince your app to create new windows, frames, or other renderer processes with more privileges than they had before; or with pages opened that they couldn't open before.

If you have no need to create windows in addition to the ones you know you'll need to create, disabling the creation buys you a little bit of extra security at no cost. This is commonly the case for apps that open one BrowserWindow and do not need to open an arbitrary number of additional windows at runtime.

How?

webContents will emit the new-window event before creating new windows. That event will be passed, amongst other parameters, the url the window was requested to open and the options used to create it. We recommend that you use the event to scrutinize the creation of windows, limiting it to only what you need.

const { shell } = require('electron')

app.on('web-contents-created', (event, contents) => {
  contents.on('new-window', (event, navigationUrl) => {
    // In this example, we'll ask the operating system
    // to open this event's url in the default browser.
    event.preventDefault()

    shell.openExternal(navigationUrl)
  })
})

SegmentedControlSegment Object

  • label String (optional) - The text to appear in this segment
  • icon NativeImage (optional) - The image to appear in this segment
  • enabled Boolean (optional) - Whether this segment is selectable. Default: true

session

Manage browser sessions, cookies, cache, proxy settings, etc.

Process: Main

The session module can be used to create new Session objects.

You can also access the session of existing pages by using the session property of WebContents, or from the session module.

const {BrowserWindow} = require('electron')

let win = new BrowserWindow({width: 800, height: 600})
win.loadURL('http://github.com')

const ses = win.webContents.session
console.log(ses.getUserAgent())

Methods

The session module has the following methods:

session.fromPartition(partition[, options])

  • partition String
  • options Object (optional)

    • cache Boolean - Whether to enable cache.

Returns Session - A session instance from partition string. When there is an existing Session with the same partition, it will be returned; otherwise a new Session instance will be created with options.

If partition starts with persist:, the page will use a persistent session available to all pages in the app with the same partition. if there is no persist: prefix, the page will use an in-memory session. If the partition is empty then default session of the app will be returned.

To create a Session with options, you have to ensure the Session with the partition has never been used before. There is no way to change the options of an existing Session object.

Properties

The session module has the following properties:

session.defaultSession

A Session object, the default session object of the app.

Class: Session

Get and set properties of a session.

Process: Main

You can create a Session object in the session module:

const {session} = require('electron')
const ses = session.fromPartition('persist:name')
console.log(ses.getUserAgent())

Instance Events

The following events are available on instances of Session:

Event: 'will-download'

Emitted when Electron is about to download item in webContents.

Calling event.preventDefault() will cancel the download and item will not be available from next tick of the process.

const {session} = require('electron')
session.defaultSession.on('will-download', (event, item, webContents) => {
  event.preventDefault()
  require('request')(item.getURL(), (data) => {
    require('fs').writeFileSync('/somewhere', data)
  })
})

Instance Methods

The following methods are available on instances of Session:

ses.getCacheSize(callback)

  • callback Function

    • size Integer - Cache size used in bytes.

Callback is invoked with the session's current cache size.

ses.clearCache(callback)

  • callback Function - Called when operation is done.

Clears the session’s HTTP cache.

ses.clearStorageData([options, callback])

  • options Object (optional)

    • origin String (optional) - Should follow window.location.origin’s representation scheme://host:port.
    • storages String - The types of storages to clear, can contain: appcache, cookies, filesystem, indexdb, localstorage, shadercache, websql, serviceworkers, cachestorage.
    • quotas String - The types of quotas to clear, can contain: temporary, persistent, syncable.
  • callback Function (optional) - Called when operation is done.

Clears the data of web storages.

ses.flushStorageData()

Writes any unwritten DOMStorage data to disk.

ses.setProxy(config, callback)

  • config Object

    • pacScript String - The URL associated with the PAC file.
    • proxyRules String - Rules indicating which proxies to use.
    • proxyBypassRules String - Rules indicating which URLs should bypass the proxy settings.
  • callback Function - Called when operation is done.

Sets the proxy settings.

When pacScript and proxyRules are provided together, the proxyRules option is ignored and pacScript configuration is applied.

The proxyRules has to follow the rules below:

proxyRules = schemeProxies[";"<schemeProxies>]
schemeProxies = [<urlScheme>"="]<proxyURIList>
urlScheme = "http" | "https" | "ftp" | "socks"
proxyURIList = <proxyURL>[","<proxyURIList>]
proxyURL = [<proxyScheme>"://"]<proxyHost>[":"<proxyPort>]

For example:

  • http=foopy:80;ftp=foopy2 - Use HTTP proxy foopy:80 for http:// URLs, and HTTP proxy foopy2:80 for ftp:// URLs.
  • foopy:80 - Use HTTP proxy foopy:80 for all URLs.
  • foopy:80,bar,direct:// - Use HTTP proxy foopy:80 for all URLs, failing over to bar if foopy:80 is unavailable, and after that using no proxy.
  • socks4://foopy - Use SOCKS v4 proxy foopy:1080 for all URLs.
  • http=foopy,socks5://bar.com - Use HTTP proxy foopy for http URLs, and fail over to the SOCKS5 proxy bar.com if foopy is unavailable.
  • http=foopy,direct:// - Use HTTP proxy foopy for http URLs, and use no proxy if foopy is unavailable.
  • http=foopy;socks=foopy2 - Use HTTP proxy foopy for http URLs, and use socks4://foopy2 for all other URLs.

The proxyBypassRules is a comma separated list of rules described below:

  • [ URL_SCHEME "://" ] HOSTNAME_PATTERN [ ":" <port> ]

    Match all hostnames that match the pattern HOSTNAME_PATTERN.

    Examples: "foobar.com", "foobar.com", ".foobar.com", "foobar.com:99", "https://x..y.com:99"

  • "." HOSTNAME_SUFFIX_PATTERN [ ":" PORT ]

    Match a particular domain suffix.

    Examples: ".google.com", ".com", "http://.google.com"

  • [ SCHEME "://" ] IP_LITERAL [ ":" PORT ]

    Match URLs which are IP address literals.

    Examples: "127.0.1", "[0:0::1]", "[::1]", "http://[::1]:99"

  • IP_LITERAL "/" PREFIX_LENGTH_IN_BITS

    Match any URL that is to an IP literal that falls between the given range. IP range is specified using CIDR notation.

    Examples: "192.168.1.1/16", "fefe:13::abc/33".

  • <local>

    Match local addresses. The meaning of <local> is whether the host matches one of: "127.0.0.1", "::1", "localhost".

ses.resolveProxy(url, callback)

  • url URL
  • callback Function

    • proxy String

Resolves the proxy information for url. The callback will be called with callback(proxy) when the request is performed.

ses.setDownloadPath(path)

  • path String - The download location.

Sets download saving directory. By default, the download directory will be the Downloads under the respective app folder.

ses.enableNetworkEmulation(options)

  • options Object

    • offline Boolean (optional) - Whether to emulate network outage. Defaults to false.
    • latency Double (optional) - RTT in ms. Defaults to 0 which will disable latency throttling.
    • downloadThroughput Double (optional) - Download rate in Bps. Defaults to 0 which will disable download throttling.
    • uploadThroughput Double (optional) - Upload rate in Bps. Defaults to 0 which will disable upload throttling.

Emulates network with the given configuration for the session.

// To emulate a GPRS connection with 50kbps throughput and 500 ms latency.
window.webContents.session.enableNetworkEmulation({
  latency: 500,
  downloadThroughput: 6400,
  uploadThroughput: 6400
})

// To emulate a network outage.
window.webContents.session.enableNetworkEmulation({offline: true})

ses.disableNetworkEmulation()

Disables any network emulation already active for the session. Resets to the original network configuration.

ses.setCertificateVerifyProc(proc)

  • proc Function

    • request Object

      • hostname String
      • certificate Certificate
      • verificationResult String - Verification result from chromium.
      • errorCode Integer - Error code.
    • callback Function

      • verificationResult Integer - Value can be one of certificate error codes from here. Apart from the certificate error codes, the following special codes can be used.

        • 0 - Indicates success and disables Certificate Transparency verification.
        • -2 - Indicates failure.
        • -3 - Uses the verification result from chromium.

Sets the certificate verify proc for session, the proc will be called with proc(request, callback) whenever a server certificate verification is requested. Calling callback(0) accepts the certificate, calling callback(-2) rejects it.

Calling setCertificateVerifyProc(null) will revert back to default certificate verify proc.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()

win.webContents.session.setCertificateVerifyProc((request, callback) => {
  const {hostname} = request
  if (hostname === 'github.com') {
    callback(0)
  } else {
    callback(-2)
  }
})

ses.setPermissionRequestHandler(handler)

  • handler Function | null

    • webContents WebContents - WebContents requesting the permission.
    • permission String - Enum of 'media', 'geolocation', 'notifications', 'midiSysex', 'pointerLock', 'fullscreen', 'openExternal'.
    • callback Function

      • permissionGranted Boolean - Allow or deny the permission.
    • details Object - Some properties are only available on certain permission types.

      • externalURL String - The url of the openExternal request.

Sets the handler which can be used to respond to permission requests for the session. Calling callback(true) will allow the permission and callback(false) will reject it. To clear the handler, call setPermissionRequestHandler(null).

const {session} = require('electron')
session.fromPartition('some-partition').setPermissionRequestHandler((webContents, permission, callback) => {
  if (webContents.getURL() === 'some-host' && permission === 'notifications') {
    return callback(false) // denied.
  }

  callback(true)
})

ses.clearHostResolverCache([callback])

  • callback Function (optional) - Called when operation is done.

Clears the host resolver cache.

ses.allowNTLMCredentialsForDomains(domains)

  • domains String - A comma-separated list of servers for which integrated authentication is enabled.

Dynamically sets whether to always send credentials for HTTP NTLM or Negotiate authentication.

const {session} = require('electron')
// consider any url ending with `example.com`, `foobar.com`, `baz`
// for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*example.com, *foobar.com, *baz')

// consider all urls for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*')

ses.setUserAgent(userAgent[, acceptLanguages])

  • userAgent String
  • acceptLanguages String (optional)

Overrides the userAgent and acceptLanguages for this session.

The acceptLanguages must a comma separated ordered list of language codes, for example "en-US,fr,de,ko,zh-CN,ja".

This doesn't affect existing WebContents, and each WebContents can use webContents.setUserAgent to override the session-wide user agent.

ses.getUserAgent()

Returns String - The user agent for this session.

ses.getBlobData(identifier, callback)

  • identifier String - Valid UUID.
  • callback Function

    • result Buffer - Blob data.

ses.createInterruptedDownload(options)

  • options Object

    • path String - Absolute path of the download.
    • urlChain String[] - Complete URL chain for the download.
    • mimeType String (optional)
    • offset Integer - Start range for the download.
    • length Integer - Total length of the download.
    • lastModified String - Last-Modified header value.
    • eTag String - ETag header value.
    • startTime Double (optional) - Time when download was started in number of seconds since UNIX epoch.

Allows resuming cancelled or interrupted downloads from previous Session. The API will generate a DownloadItem that can be accessed with the will-download event. The DownloadItem will not have any WebContents associated with it and the initial state will be interrupted. The download will start only when the resume API is called on the DownloadItem.

ses.clearAuthCache(options[, callback])

Clears the session’s HTTP authentication cache.

ses.setPreloads(preloads)

  • preloads String[] - An array of absolute path to preload scripts

Adds scripts that will be executed on ALL web contents that are associated with this session just before normal preload scripts run.

ses.getPreloads()

Returns String[] an array of paths to preload scripts that have been registered.

Instance Properties

The following properties are available on instances of Session:

ses.cookies

A Cookies object for this session.

ses.webRequest

A WebRequest object for this session.

ses.protocol

A Protocol object for this session.

const {app, session} = require('electron')
const path = require('path')

app.on('ready', function () {
  const protocol = session.fromPartition('some-partition').protocol
  protocol.registerFileProtocol('atom', function (request, callback) {
    var url = request.url.substr(7)
    callback({path: path.normalize(`${__dirname}/${url}`)})
  }, function (error) {
    if (error) console.error('Failed to register protocol')
  })
})

Setting Up Symbol Server in Debugger

Debug symbols allow you to have better debugging sessions. They have information about the functions contained in executables and dynamic libraries and provide you with information to get clean call stacks. A Symbol Server allows the debugger to load the correct symbols, binaries and sources automatically without forcing users to download large debugging files. The server functions like Microsoft's symbol server so the documentation there can be useful.

Note that because released Electron builds are heavily optimized, debugging is not always easy. The debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations. The only workaround is to build an unoptimized local build.

The official symbol server URL for Electron is https://electron-symbols.githubapp.com. You cannot visit this URL directly, you must add it to the symbol path of your debugging tool. In the examples below, a local cache directory is used to avoid repeatedly fetching the PDB from the server. Replace c:\code\symbols with an appropriate cache directory on your machine.

Using the Symbol Server in Windbg

The Windbg symbol path is configured with a string value delimited with asterisk characters. To use only the Electron symbol server, add the following entry to your symbol path (Note: you can replace c:\code\symbols with any writable directory on your computer, if you'd prefer a different location for downloaded symbols):

SRV*c:\code\symbols\*https://electron-symbols.githubapp.com

Set this string as _NT_SYMBOL_PATH in the environment, using the Windbg menus, or by typing the .sympath command. If you would like to get symbols from Microsoft's symbol server as well, you should list that first:

SRV*c:\code\symbols\*https://msdl.microsoft.com/download/symbols;SRV*c:\code\symbols\*https://electron-symbols.githubapp.com

Troubleshooting: Symbols will not load

Type the following commands in Windbg to print why symbols are not loading:

> !sym noisy
> .reload /f electron.exe

shell

Manage files and URLs using their default applications.

Process: Main, Renderer

The shell module provides functions related to desktop integration.

An example of opening a URL in the user's default browser:

const {shell} = require('electron')

shell.openExternal('https://github.com')

Methods

The shell module has the following methods:

shell.showItemInFolder(fullPath)

  • fullPath String

Returns Boolean - Whether the item was successfully shown.

Show the given file in a file manager. If possible, select the file.

shell.openItem(fullPath)

  • fullPath String

Returns Boolean - Whether the item was successfully opened.

Open the given file in the desktop's default manner.

shell.openExternal(url[, options, callback])

  • url String - Max 2081 characters on windows, or the function returns false.
  • options Object (optional) macOS

    • activate Boolean - true to bring the opened application to the foreground. The default is true.
  • callback Function (optional) macOS - If specified will perform the open asynchronously.

    • error Error

Returns Boolean - Whether an application was available to open the URL. If callback is specified, always returns true.

Open the given external protocol URL in the desktop's default manner. (For example, mailto: URLs in the user's default mail agent).

shell.moveItemToTrash(fullPath)

  • fullPath String

Returns Boolean - Whether the item was successfully moved to the trash.

Move the given file to trash and returns a boolean status for the operation.

shell.beep()

Play the beep sound.

shell.writeShortcutLink(shortcutPath[, operation], options) Windows

  • shortcutPath String
  • operation String (optional) - Default is create, can be one of following:

    • create - Creates a new shortcut, overwriting if necessary.
    • update - Updates specified properties only on an existing shortcut.
    • replace - Overwrites an existing shortcut, fails if the shortcut doesn't exist.
  • options ShortcutDetails

Returns Boolean - Whether the shortcut was created successfully.

Creates or updates a shortcut link at shortcutPath.

shell.readShortcutLink(shortcutPath) Windows

  • shortcutPath String

Returns ShortcutDetails

Resolves the shortcut link at shortcutPath.

An exception will be thrown when any error happens.


ShortcutDetails Object

  • target String - The target to launch from this shortcut.
  • cwd String (optional) - The working directory. Default is empty.
  • args String (optional) - The arguments to be applied to target when launching from this shortcut. Default is empty.
  • description String (optional) - The description of the shortcut. Default is empty.
  • icon String (optional) - The path to the icon, can be a DLL or EXE. icon and iconIndex have to be set together. Default is empty, which uses the target's icon.
  • iconIndex Number (optional) - The resource ID of icon when icon is a DLL or EXE. Default is 0.
  • appUserModelId String (optional) - The Application User Model ID. Default is empty.

Size Object

  • width Number
  • height Number

Snapcraft Guide (Ubuntu Software Center & More)

This guide provides information on how to package your Electron application for any Snapcraft environment, including the Ubuntu Software Center.

Background and Requirements

Together with the broader Linux community, Canonical aims to fix many of the common software installation problems with the snapcraft project. Snaps are containerized software packages that include required dependencies, auto-update, and work on all major Linux distributions without system modification.

There are three ways to create a .snap file:

1) Using electron-forge or electron-builder, both tools that come with snap support out of the box. This is the easiest option. 2) Using electron-installer-snap, which takes electron-packager's output. 3) Using an already created .deb package.

In all cases, you will need to have the snapcraft tool installed. We recommend building on Ubuntu 16.04 (or the current LTS).

snap install snapcraft --classic

While it is possible to install snapcraft on macOS using Homebrew, it is not able to build snap packages and is focused on managing packages in the store.

Using electron-installer-snap

The module works like electron-winstaller and similar modules in that its scope is limited to building snap packages. You can install it with:

npm install --save-dev electron-installer-snap

Step 1: Package Your Electron Application

Package the application using electron-packager (or a similar tool). Make sure to remove node_modules that you don't need in your final application, since any module you don't actually need will increase your application's size.

The output should look roughly like this:

.
└── dist
    └── app-linux-x64
        ├── LICENSE
        ├── LICENSES.chromium.html
        ├── content_shell.pak
        ├── app
        ├── icudtl.dat
        ├── libgcrypt.so.11
        ├── libnode.so
        ├── locales
        ├── natives_blob.bin
        ├── resources
        ├── v8_context_snapshot.bin
        └── version

Step 2: Running electron-installer-snap

From a terminal that has snapcraft in its PATH, run electron-installer-snap with the only required parameter --src, which is the location of your packaged Electron application created in the first step.

npx electron-installer-snap --src=out/myappname-linux-x64

If you have an existing build pipeline, you can use electron-installer-snap programmatically. For more information, see the Snapcraft API docs.

const snap = require('electron-installer-snap')

snap(options)
  .then(snapPath => console.log(`Created snap at ${snapPath}!`))

Using an Existing Debian Package

Snapcraft is capable of taking an existing .deb file and turning it into a .snap file. The creation of a snap is configured using a snapcraft.yaml file that describes the sources, dependencies, description, and other core building blocks.

Step 1: Create a Debian Package

If you do not already have a .deb package, using electron-installer-snap might be an easier path to create snap packages. However, multiple solutions for creating Debian packages exist, including electron-forge, electron-builder or electron-installer-debian.

Step 2: Create a snapcraft.yaml

For more information on the available configuration options, see the documentation on the snapcraft syntax. Let's look at an example:

name: myApp
version: '2.0.0'
summary: A little description for the app.
description: |
 You know what? This app is amazing! It does all the things
 for you. Some say it keeps you young, maybe even happy.

grade: stable
confinement: classic

parts:
  slack:
    plugin: dump
    source: my-deb.deb
    source-type: deb
    after:
      - desktop-gtk3
    stage-packages:
      - libasound2
      - libgconf2-4
      - libnotify4
      - libnspr4
      - libnss3
      - libpcre3
      - libpulse0
      - libxss1
      - libxtst6
  electron-launch:
    plugin: dump
    source: files/
    prepare: |
      chmod +x bin/electron-launch

apps:
  myApp:
    command: bin/electron-launch $SNAP/usr/lib/myApp/myApp
    desktop: usr/share/applications/myApp.desktop
    # Correct the TMPDIR path for Chromium Framework/Electron to ensure
    # libappindicator has readable resources.
    environment:
      TMPDIR: $XDG_RUNTIME_DIR

As you can see, the snapcraft.yaml instructs the system to launch a file called electron-launch. In this example, it passes information on to the app's binary:

#!/bin/sh

exec "$@" --executed-from="$(pwd)" --pid=$$ > /dev/null 2>&1 &

Alternatively, if you're building your snap with strict confinement, you can use the desktop-launch command:

apps:
  myApp:
    # Correct the TMPDIR path for Chromium Framework/Electron to ensure
    # libappindicator has readable resources.
    command: env TMPDIR=$XDG_RUNTIME_DIR PATH=/usr/local/bin:${PATH} ${SNAP}/bin/desktop-launch $SNAP/myApp/desktop
    desktop: usr/share/applications/desktop.desktop

Source Code Directory Structure

The source code of Electron is separated into a few parts, mostly following Chromium on the separation conventions.

You may need to become familiar with Chromium's multi-process architecture to understand the source code better.

Structure of Source Code

Electron
├── atom/ - C++ source code.
|   ├── app/ - System entry code.
|   ├── browser/ - The frontend including the main window, UI, and all of the
|   |   |          main process things. This talks to the renderer to manage web
|   |   |          pages.
|   |   ├── ui/ - Implementation of UI stuff for different platforms.
|   |   |   ├── cocoa/ - Cocoa specific source code.
|   |   |   ├── win/ - Windows GUI specific source code.
|   |   |   └── x/ - X11 specific source code.
|   |   ├── api/ - The implementation of the main process APIs.
|   |   ├── net/ - Network related code.
|   |   ├── mac/ - Mac specific Objective-C source code.
|   |   └── resources/ - Icons, platform-dependent files, etc.
|   ├── renderer/ - Code that runs in renderer process.
|   |   └── api/ - The implementation of renderer process APIs.
|   └── common/ - Code that used by both the main and renderer processes,
|       |         including some utility functions and code to integrate node's
|       |         message loop into Chromium's message loop.
|       └── api/ - The implementation of common APIs, and foundations of
|                  Electron's built-in modules.
├── chromium_src/ - Source code copied from Chromium. See below.
├── default_app/ - The default page to show when Electron is started without
|                  providing an app.
├── docs/ - Documentations.
├── lib/ - JavaScript source code.
|   ├── browser/ - Javascript main process initialization code.
|   |   └── api/ - Javascript API implementation.
|   ├── common/ - JavaScript used by both the main and renderer processes
|   |   └── api/ - Javascript API implementation.
|   └── renderer/ - Javascript renderer process initialization code.
|       └── api/ - Javascript API implementation.
├── native_mate/ - A fork of Chromium's gin library that makes it easier to marshal
|                  types between C++ and JavaScript.
├── spec/ - Automatic tests.
└── BUILD.gn - Building rules of Electron.

/chromium_src

The files in /chromium_src tend to be pieces of Chromium that aren't part of the content layer. For example to implement Pepper API, we need some wiring similar to what official Chrome does. We could have built the relevant sources as a part of libcc but most often we don't require all the features (some tend to be proprietary, analytics stuff) so we took parts of the code. These could have easily been patches in libcc, but at the time when these were written the goal of libcc was to maintain very minimal patches and chromium_src changes tend to be big ones. Also, note that these patches can never be upstreamed unlike other libcc patches we maintain now.

Structure of Other Directories

  • script - Scripts used for development purpose like building, packaging, testing, etc.
  • tools - Helper scripts used by GN files, unlike script, scripts put here should never be invoked by users directly.
  • vendor - Source code of third party dependencies, we didn't use third_party as name because it would confuse it with the same directory in Chromium's source code tree.
  • node_modules - Third party node modules used for building.
  • out - Temporary output directory of ninja.
  • dist - Temporary directory created by script/create-dist.py script when creating a distribution.
  • external_binaries - Downloaded binaries of third-party frameworks which do not support building with gn.

Keeping Git Submodules Up to Date

The Electron repository has a few vendored dependencies, found in the /vendor directory. Occasionally you might see a message like this when running git status:

$ git status

	modified:   vendor/depot_tools (new commits)
	modified:   vendor/boto (new commits)

To update these vendored dependencies, run the following command:

git submodule update --init --recursive

If you find yourself running this command often, you can create an alias for it in your ~/.gitconfig file:

[alias]
	su = submodule update --init --recursive

StreamProtocolResponse Object

  • statusCode Number - The HTTP response code
  • headers Object - An object containing the response headers
  • data ReadableStream - A Node.js readable stream representing the response body

Electron Documentation Styleguide

These are the guidelines for writing Electron documentation.

Titles

  • Each page must have a single #-level title at the top.
  • Chapters in the same page must have ##-level titles.
  • Sub-chapters need to increase the number of # in the title according to their nesting depth.
  • All words in the page's title must be capitalized, except for conjunctions like "of" and "and" .
  • Only the first word of a chapter title must be capitalized.

Using Quick Start as example:

# Quick Start

...

## Main process

...

## Renderer process

...

## Run your app

...

### Run as a distribution

...

### Manually downloaded Electron binary

...

For API references, there are exceptions to this rule.

Markdown rules

  • Use sh instead of cmd in code blocks (due to the syntax highlighter).
  • Lines should be wrapped at 80 columns.
  • No nesting lists more than 2 levels (due to the markdown renderer).
  • All js and javascript code blocks are linted with standard-markdown.

Picking words

  • Use "will" over "would" when describing outcomes.
  • Prefer "in the ___ process" over "on".

API references

The following rules only apply to the documentation of APIs.

Page title

Each page must use the actual object name returned by require('electron') as the title, such as BrowserWindow, autoUpdater, and session.

Under the page title must be a one-line description starting with >.

Using session as example:

# session

> Manage browser sessions, cookies, cache, proxy settings, etc.

Module methods and events

For modules that are not classes, their methods and events must be listed under the ## Methods and ## Events chapters.

Using autoUpdater as an example:

# autoUpdater

## Events

### Event: 'error'

## Methods

### `autoUpdater.setFeedURL(url[, requestHeaders])`

Classes

  • API classes or classes that are part of modules must be listed under a ## Class: TheClassName chapter.
  • One page can have multiple classes.
  • Constructors must be listed with ###-level titles.
  • Static Methods must be listed under a ### Static Methods chapter.
  • Instance Methods must be listed under an ### Instance Methods chapter.
  • All methods that have a return value must start their description with "Returns [TYPE] - Return description"

    • If the method returns an Object, its structure can be specified using a colon followed by a newline then an unordered list of properties in the same style as function parameters.
  • Instance Events must be listed under an ### Instance Events chapter.
  • Instance Properties must be listed under an ### Instance Properties chapter.

    • Instance properties must start with "A [Property Type] ..."

Using the Session and Cookies classes as an example:

# session

## Methods

### session.fromPartition(partition)

## Properties

### session.defaultSession

## Class: Session

### Instance Events

#### Event: 'will-download'

### Instance Methods

#### `ses.getCacheSize(callback)`

### Instance Properties

#### `ses.cookies`

## Class: Cookies

### Instance Methods

#### `cookies.get(filter, callback)`

Methods

The methods chapter must be in the following form:

### `objectName.methodName(required[, optional]))`

* `required` String - A parameter description.
* `optional` Integer (optional) - Another parameter description.

...

The title can be ### or ####-levels depending on whether it is a method of a module or a class.

For modules, the objectName is the module's name. For classes, it must be the name of the instance of the class, and must not be the same as the module's name.

For example, the methods of the Session class under the session module must use ses as the objectName.

The optional arguments are notated by square brackets [] surrounding the optional argument as well as the comma required if this optional argument follows another argument:

required[, optional]

Below the method is more detailed information on each of the arguments. The type of argument is notated by either the common types:

If an argument or a method is unique to certain platforms, those platforms are denoted using a space-delimited italicized list following the datatype. Values can be macOS, Windows or Linux.

* `animate` Boolean (optional) _macOS_ _Windows_ - Animate the thing.

Array type arguments must specify what elements the array may include in the description below.

The description for Function type arguments should make it clear how it may be called and list the types of the parameters that will be passed to it.

Events

The events chapter must be in following form:

### Event: 'wake-up'

Returns:

* `time` String

...

The title can be ### or ####-levels depending on whether it is an event of a module or a class.

The arguments of an event follow the same rules as methods.

Properties

The properties chapter must be in following form:

### session.defaultSession

...

The title can be ### or ####-levels depending on whether it is a property of a module or a class.


Finding Support

If you have a security concern, please see the security document.

If you're looking for programming help, for answers to questions, or to join in discussion with other developers who use Electron, you can interact with the community in these locations:

If you'd like to contribute to Electron, see the contributing document.

If you've found a bug in a supported version of Electron, please report it with the issue tracker.

awesome-electron is a community-maintained list of useful example apps, tools and resources.

Supported Versions

The latest three release branches are supported by the Electron team. For example, if the latest release is 2.0.x, then the 2-0-x series is supported, as are the two previous release series 1-7-x and 1-8-x.

When a release branch reaches the end of its support cycle, the series will be deprecated in NPM and a final end-of-support release will be made. This release will add a warning to inform that an unsupported version of Electron is in use.

These steps are to help app developers learn when a branch they're using becomes unsupported, but without being excessively intrusive to end users.

If an application has exceptional circumstances and needs to stay on an unsupported series of Electron, developers can silence the end-of-support warning by omitting the final release from the app's package.json devDependencies. For example, since the 1-6-x series ended with an end-of-support 1.6.18 release, developers could choose to stay in the 1-6-x series without warnings with devDependency of "electron": 1.6.0 - 1.6.17.

Supported Platforms

Following platforms are supported by Electron:

macOS

Only 64bit binaries are provided for macOS, and the minimum macOS version supported is macOS 10.10 (Yosemite).

Windows

Windows 7 and later are supported, older operating systems are not supported (and do not work).

Both ia32 (x86) and x64 (amd64) binaries are provided for Windows. Running Electron apps on Windows for ARM devices is possible by using the ia32 binary.

Linux

The prebuilt ia32 (i686) and x64 (amd64) binaries of Electron are built on Ubuntu 12.04, the armv7l binary is built against ARM v7 with hard-float ABI and NEON for Debian Wheezy.

Until the release of Electron 2.0, Electron will also continue to release the armv7l binary with a simple arm suffix. Both binaries are identical.

Whether the prebuilt binary can run on a distribution depends on whether the distribution includes the libraries that Electron is linked to on the building platform, so only Ubuntu 12.04 is guaranteed to work, but following platforms are also verified to be able to run the prebuilt binaries of Electron:

  • Ubuntu 12.04 and newer
  • Fedora 21
  • Debian 8

Moved to support.md


Synopsis

How to use Node.js and Electron APIs.

All of Node.js's built-in modules are available in Electron and third-party node modules also fully supported as well (including the native modules).

Electron also provides some extra built-in modules for developing native desktop applications. Some modules are only available in the main process, some are only available in the renderer process (web page), and some can be used in both processes.

The basic rule is: if a module is GUI or low-level system related, then it should be only available in the main process. You need to be familiar with the concept of main process vs. renderer process scripts to be able to use those modules.

The main process script is like a normal Node.js script:

const {app, BrowserWindow} = require('electron')
let win = null

app.on('ready', () => {
  win = new BrowserWindow({width: 800, height: 600})
  win.loadURL('https://github.com')
})

The renderer process is no different than a normal web page, except for the extra ability to use node modules:

<!DOCTYPE html>
<html>
<body>
<script>
  const {app} = require('electron').remote
  console.log(app.getVersion())
</script>
</body>
</html>

To run your app, read Run your app.

Destructuring assignment

As of 0.37, you can use destructuring assignment to make it easier to use built-in modules.

const {app, BrowserWindow} = require('electron')

let win

app.on('ready', () => {
  win = new BrowserWindow()
  win.loadURL('https://github.com')
})

If you need the entire electron module, you can require it and then using destructuring to access the individual modules from electron.

const electron = require('electron')
const {app, BrowserWindow} = electron

let win

app.on('ready', () => {
  win = new BrowserWindow()
  win.loadURL('https://github.com')
})

This is equivalent to the following code:

const electron = require('electron')
const app = electron.app
const BrowserWindow = electron.BrowserWindow
let win

app.on('ready', () => {
  win = new BrowserWindow()
  win.loadURL('https://github.com')
})

systemPreferences

Get system preferences.

Process: Main

const {systemPreferences} = require('electron')
console.log(systemPreferences.isDarkMode())

Events

The systemPreferences object emits the following events:

Event: 'accent-color-changed' Windows

Returns:

  • event Event
  • newColor String - The new RGBA color the user assigned to be their system accent color.

Event: 'color-changed' Windows

Returns:

  • event Event

Event: 'inverted-color-scheme-changed' Windows

Returns:

  • event Event
  • invertedColorScheme Boolean - true if an inverted color scheme, such as a high contrast theme, is being used, false otherwise.

systemPreferences.isDarkMode() macOS

Returns Boolean - Whether the system is in Dark Mode.

systemPreferences.isSwipeTrackingFromScrollEventsEnabled() macOS

Returns Boolean - Whether the Swipe between pages setting is on.

systemPreferences.postNotification(event, userInfo) macOS

  • event String
  • userInfo Object

Posts event as native notifications of macOS. The userInfo is an Object that contains the user information dictionary sent along with the notification.

systemPreferences.postLocalNotification(event, userInfo) macOS

  • event String
  • userInfo Object

Posts event as native notifications of macOS. The userInfo is an Object that contains the user information dictionary sent along with the notification.

systemPreferences.postWorkspaceNotification(event, userInfo) macOS

  • event String
  • userInfo Object

Posts event as native notifications of macOS. The userInfo is an Object that contains the user information dictionary sent along with the notification.

systemPreferences.subscribeNotification(event, callback) macOS

  • event String

  • callback Function

    • event String
    • userInfo Object

Returns Number - The ID of this subscription

Subscribes to native notifications of macOS, callback will be called with callback(event, userInfo) when the corresponding event happens. The userInfo is an Object that contains the user information dictionary sent along with the notification.

The id of the subscriber is returned, which can be used to unsubscribe the event.

Under the hood this API subscribes to NSDistributedNotificationCenter, example values of event are:

  • AppleInterfaceThemeChangedNotification
  • AppleAquaColorVariantChanged
  • AppleColorPreferencesChangedNotification
  • AppleShowScrollBarsSettingChanged

systemPreferences.subscribeLocalNotification(event, callback) macOS

  • event String

  • callback Function

    • event String
    • userInfo Object

Returns Number - The ID of this subscription

Same as subscribeNotification, but uses NSNotificationCenter for local defaults. This is necessary for events such as NSUserDefaultsDidChangeNotification.

systemPreferences.subscribeWorkspaceNotification(event, callback) macOS

  • event String
  • callback Function

    • event String
    • userInfo Object

Same as subscribeNotification, but uses NSWorkspace.sharedWorkspace.notificationCenter. This is necessary for events such as NSWorkspaceDidActivateApplicationNotification.

systemPreferences.unsubscribeNotification(id) macOS

  • id Integer

Removes the subscriber with id.

systemPreferences.unsubscribeLocalNotification(id) macOS

  • id Integer

Same as unsubscribeNotification, but removes the subscriber from NSNotificationCenter.

systemPreferences.unsubscribeWorkspaceNotification(id) macOS

  • id Integer

Same as unsubscribeNotification, but removes the subscriber from NSWorkspace.sharedWorkspace.notificationCenter.

systemPreferences.registerDefaults(defaults) macOS

  • defaults Object - a dictionary of (key: value) user defaults

Add the specified defaults to your application's NSUserDefaults.

systemPreferences.getUserDefault(key, type) macOS

  • key String
  • type String - Can be string, boolean, integer, float, double, url, array or dictionary.

Returns any - The value of key in NSUserDefaults.

Some popular key and types are:

  • AppleInterfaceStyle: string
  • AppleAquaColorVariant: integer
  • AppleHighlightColor: string
  • AppleShowScrollBars: string
  • NSNavRecentPlaces: array
  • NSPreferredWebServices: dictionary
  • NSUserDictionaryReplacementItems: array

systemPreferences.setUserDefault(key, type, value) macOS

Set the value of key in NSUserDefaults.

Note that type should match actual type of value. An exception is thrown if they don't.

Some popular key and types are:

  • ApplePressAndHoldEnabled: boolean

systemPreferences.removeUserDefault(key) macOS

  • key String

Removes the key in NSUserDefaults. This can be used to restore the default or global value of a key previously set with setUserDefault.

systemPreferences.isAeroGlassEnabled() Windows

Returns Boolean - true if DWM composition (Aero Glass) is enabled, and false otherwise.

An example of using it to determine if you should create a transparent window or not (transparent windows won't work correctly when DWM composition is disabled):

const {BrowserWindow, systemPreferences} = require('electron')
let browserOptions = {width: 1000, height: 800}

// Make the window transparent only if the platform supports it.
if (process.platform !== 'win32' || systemPreferences.isAeroGlassEnabled()) {
  browserOptions.transparent = true
  browserOptions.frame = false
}

// Create the window.
let win = new BrowserWindow(browserOptions)

// Navigate.
if (browserOptions.transparent) {
  win.loadURL(`file://${__dirname}/index.html`)
} else {
  // No transparency, so we load a fallback that uses basic styles.
  win.loadURL(`file://${__dirname}/fallback.html`)
}

systemPreferences.getAccentColor() Windows

Returns String - The users current system wide accent color preference in RGBA hexadecimal form.

const color = systemPreferences.getAccentColor() // `"aabbccdd"`
const red = color.substr(0, 2) // "aa"
const green = color.substr(2, 2) // "bb"
const blue = color.substr(4, 2) // "cc"
const alpha = color.substr(6, 2) // "dd"

systemPreferences.getColor(color) Windows

  • color String - One of the following values:

    • 3d-dark-shadow - Dark shadow for three-dimensional display elements.
    • 3d-face - Face color for three-dimensional display elements and for dialog box backgrounds.
    • 3d-highlight - Highlight color for three-dimensional display elements.
    • 3d-light - Light color for three-dimensional display elements.
    • 3d-shadow - Shadow color for three-dimensional display elements.
    • active-border - Active window border.
    • active-caption - Active window title bar. Specifies the left side color in the color gradient of an active window's title bar if the gradient effect is enabled.
    • active-caption-gradient - Right side color in the color gradient of an active window's title bar.
    • app-workspace - Background color of multiple document interface (MDI) applications.
    • button-text - Text on push buttons.
    • caption-text - Text in caption, size box, and scroll bar arrow box.
    • desktop - Desktop background color.
    • disabled-text - Grayed (disabled) text.
    • highlight - Item(s) selected in a control.
    • highlight-text - Text of item(s) selected in a control.
    • hotlight - Color for a hyperlink or hot-tracked item.
    • inactive-border - Inactive window border.
    • inactive-caption - Inactive window caption. Specifies the left side color in the color gradient of an inactive window's title bar if the gradient effect is enabled.
    • inactive-caption-gradient - Right side color in the color gradient of an inactive window's title bar.
    • inactive-caption-text - Color of text in an inactive caption.
    • info-background - Background color for tooltip controls.
    • info-text - Text color for tooltip controls.
    • menu - Menu background.
    • menu-highlight - The color used to highlight menu items when the menu appears as a flat menu.
    • menubar - The background color for the menu bar when menus appear as flat menus.
    • menu-text - Text in menus.
    • scrollbar - Scroll bar gray area.
    • window - Window background.
    • window-frame - Window frame.
    • window-text - Text in windows.

Returns String - The system color setting in RGB hexadecimal form (#ABCDEF). See the Windows docs for more details.

systemPreferences.isInvertedColorScheme() Windows

Returns Boolean - true if an inverted color scheme, such as a high contrast theme, is active, false otherwise.


Task Object

  • program String - Path of the program to execute, usually you should specify process.execPath which opens the current program.
  • arguments String - The command line arguments when program is executed.
  • title String - The string to be displayed in a JumpList.
  • description String - Description of this task.
  • iconPath String - The absolute path to an icon to be displayed in a JumpList, which can be an arbitrary resource file that contains an icon. You can usually specify process.execPath to show the icon of the program.
  • iconIndex Number - The icon index in the icon file. If an icon file consists of two or more icons, set this value to identify the icon. If an icon file consists of one icon, this value is 0.

Testing

We aim to keep the code coverage of Electron high. We ask that all pull request not only pass all existing tests, but ideally also add new tests to cover changed code and new scenarios. Ensuring that we capture as many code paths and use cases of Electron as possible ensures that we all ship apps with fewer bugs.

This repository comes with linting rules for both JavaScript and C++ – as well as unit and integration tests. To learn more about Electron's coding style, please see the coding-style document.

Linting

To ensure that your JavaScript is in compliance with the Electron coding style, run npm run lint-js, which will run standard against both Electron itself as well as the unit tests. If you are using an editor with a plugin/addon system, you might want to use one of the many StandardJS addons to be informed of coding style violations before you ever commit them.

To run standard with parameters, run npm run lint-js -- followed by arguments you want passed to standard.

To ensure that your C++ is in compliance with the Electron coding style, run npm run lint-cpp, which runs a cpplint script. We recommend that you use clang-format and prepared a short tutorial.

There is not a lot of Python in this repository, but it too is governed by coding style rules. npm run lint-py will check all Python, using pylint to do so.

Unit Tests

To run all unit tests, run npm run test. The unit tests are an Electron app (surprise!) that can be found in the spec folder. Note that it has its own package.json and that its dependencies are therefore not defined in the top-level package.json.

To run only specific tests matching a pattern, run npm run test -- -g=PATTERN, replacing the PATTERN with a regex that matches the tests you would like to run. As an example: If you want to run only IPC tests, you would run npm run test -- -g ipc.


Testing on Headless CI Systems (Travis CI, Jenkins)

Being based on Chromium, Electron requires a display driver to function. If Chromium can't find a display driver, Electron will fail to launch - and therefore not executing any of your tests, regardless of how you are running them. Testing Electron-based apps on Travis, Circle, Jenkins or similar Systems requires therefore a little bit of configuration. In essence, we need to use a virtual display driver.

Configuring the Virtual Display Server

First, install Xvfb. It's a virtual framebuffer, implementing the X11 display server protocol - it performs all graphical operations in memory without showing any screen output, which is exactly what we need.

Then, create a virtual xvfb screen and export an environment variable called DISPLAY that points to it. Chromium in Electron will automatically look for $DISPLAY, so no further configuration of your app is required. This step can be automated with Paul Betts's xvfb-maybe: Prepend your test commands with xvfb-maybe and the little tool will automatically configure xvfb, if required by the current system. On Windows or macOS, it will do nothing.

## On Windows or macOS, this invokes electron-mocha
## On Linux, if we are in a headless environment, this will be equivalent
## to xvfb-run electron-mocha ./test/*.js
xvfb-maybe electron-mocha ./test/*.js

Travis CI

On Travis, your .travis.yml should look roughly like this: