electron/docs/api/app.md

app

Control your application's event lifecycle.

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 just 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.

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.

Event: 'quit'

Returns:

• event Event
• exitCode Integer

Emitted when the application is quitting.

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. The URL scheme must be registered to be opened by your application.

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, which usually happens when the user clicks on the application's dock 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: 'browser-window-blur'

Returns:

• event Event
• window BrowserWindow

Emitted when a browserWindow gets blurred.

Event: 'browser-window-focus'

Returns:

• event Event
• window BrowserWindow

Emitted when a browserWindow gets focused.

Event: 'browser-window-created'

Returns:

• event Event
• window BrowserWindow

Emitted when a new browserWindow is created.

Event: 'web-contents-created'

Returns:

• event Event
• webContents WebContents

Emitted when a new webContents is created.

Event: 'certificate-error'

Returns:

• event Event
• webContents WebContents
• url URL
• error String - The error code
• certificate Object
  • data String - PEM encoded data
  • issuerName String - Issuer's Common Name
  • subjectName String - Subject's Common Name
  • serialNumber String - Hex value represented string
  • validStart Integer - Start date of the certificate being valid in seconds
  • validExpiry Integer - End date of the certificate being valid in seconds
  • fingerprint String - Fingerprint of the certificate
• callback Function

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:

• event Event
• webContents WebContents
• url URL
• certificateList [Objects]
  • data String - PEM encoded data
  • issuerName String - Issuer's Common Name
  • subjectName String - Subject's Common Name
  • serialNumber String - Hex value represented string
  • validStart Integer - Start date of the certificate being valid in seconds
  • validExpiry Integer - End date of the certificate being valid in seconds
  • fingerprint String - Fingerprint of the certificate
• callback Function

Emitted when a client certificate is requested.

The url corresponds to the navigation entry requesting the client certificate and callback needs to 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

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.

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 Array (optional)
  • 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) + ['--relaunch']})
app.exit(0)

app.isReady()

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

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.
• pepperFlashSystemPlugin Full path to the system version of the Pepper Flash plugin.

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.

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]) macOS Windows

• 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 Array (optional) Windows - Defaults to an empty array

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.

Returns true when the call succeeded, otherwise returns false.

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 Array (optional) Windows - Defaults to an empty array

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.

Returns true when the call succeeded, otherwise returns false.

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

• protocol String - The name of your protocol, without ://.
• path String (optional) Windows - Defaults to process.execPath
• args Array (optional) 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 Array - Array of Task objects

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

tasks is an array of Task objects in the following format:

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 Integer - 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.

Returns true when the call succeeded, otherwise returns false.

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 Array - 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

• categories Array or null - Array of JumpListCategory objects.

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 occured, 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).

JumpListCategory objects should have the following properties:

• type String - 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 - Must be set if type is custom, otherwise it should be omitted.
• items Array - 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.

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().

JumpListItem objects should have the following properties:

• type String - 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 - Path of the file to open, should only be set if type is file.
• program String - 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 - The command line arguments when program is executed. Should only be set if type is task.
• title String - The text to be displayed for the item in the Jump List. Should only be set if type is task.
• description String - Description of the task (displayed in a tooltip). Should only be set if type is task.
• iconPath String - 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 Integer - 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.

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.makeSingleInstance(callback)

• callback Function

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.

callback will be called with callback(argv, workingDirectory) 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.

The callback is guaranteed to be executed after the ready event of app gets emitted.

This method returns false if your process is the primary instance of the application and your app should continue loading. And returns true if your process has sent its parameters to another instance, and you should immediately quit.

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 shouldQuit = app.makeSingleInstance((commandLine, workingDirectory) => {
  // Someone tried to run a second instance, we should focus our window.
  if (myWindow) {
    if (myWindow.isMinimized()) myWindow.restore()
    myWindow.focus()
  }
})

if (shouldQuit) {
  app.quit()
}

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

app.releaseSingleInstance()

Releases all locks that were created by makeSingleInstance. 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 - 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.setAppUserModelId(id) Windows

• id String

Changes the Application User Model ID to id.

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.setBadgeCount(count) Linux macOS

• count Integer

Sets the counter badge for current app. Setting the count to 0 will hide the badge. Returns true when the call succeeded, otherwise returns false.

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

Note: Unity launcher requires the exsistence 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() macOS Windows

Returns Object:

• openAtLogin Boolean - true if the app is set to open at login.
• openAsHidden Boolean - true if the app is set to open as hidden at login. This setting is only supported on macOS.
• wasOpenedAtLogin Boolean - true if the app was opened at login automatically. This setting is only supported on macOS.
• wasOpenedAsHidden Boolean - 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 only supported on macOS.
• restoreState Boolean - 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 only supported on macOS.

Note: This API has no effect on MAS builds.

app.setLoginItemSettings(settings) macOS Windows

• settings Object
  • openAtLogin Boolean - true to open the app at login, false to remove the app as a login item. Defaults to false.
  • openAsHidden Boolean - true to open the app as hidden. Defaults to false. The user can edit this setting from the System Preferences so app.getLoginItemStatus().wasOpenedAsHidden should be checked when the app is opened to know the current value. This setting is only supported on macOS.

Set the app's login item settings.

Note: This API has no effect on MAS builds.

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.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.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 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

• menu Menu

Sets the application's dock menu.

app.dock.setIcon(image) macOS

• image NativeImage

Sets the image associated with this dock icon.