24 KiB
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'
Emitted when Electron has finished initialization.
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
EventexitCode
Integer
Emitted when the application is quitting.
Event: 'open-file' macOS
Returns:
event
Eventpath
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
Eventurl
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
EventhasVisibleWindows
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
Eventtype
String - A string identifying the activity. Maps toNSUserActivity.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
Eventwindow
BrowserWindow
Emitted when a browserWindow gets blurred.
Event: 'browser-window-focus'
Returns:
event
Eventwindow
BrowserWindow
Emitted when a browserWindow gets focused.
Event: 'browser-window-created'
Returns:
event
Eventwindow
BrowserWindow
Emitted when a new browserWindow is created.
Event: 'web-contents-created'
Returns:
event
EventwebContents
WebContents
Emitted when a new webContents is created.
Event: 'certificate-error'
Returns:
event
EventwebContents
WebContentsurl
URLerror
String - The error codecertificate
Objectdata
Buffer - PEM encoded dataissuerName
String - Issuer's Common NamesubjectName
String - Subject's Common NameserialNumber
String - Hex value represented stringvalidStart
Integer - Start date of the certificate being valid in secondsvalidExpiry
Integer - End date of the certificate being valid in secondsfingerprint
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
EventwebContents
WebContentsurl
URLcertificateList
[Objects]data
Buffer - PEM encoded dataissuerName
String - Issuer's Common NamesubjectName
String - Subject's Common NameserialNumber
String - Hex value represented stringvalidStart
Integer - Start date of the certificate being valid in secondsvalidExpiry
Integer - End date of the certificate being valid in secondsfingerprint
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
EventwebContents
WebContentsrequest
Objectmethod
Stringurl
URLreferrer
URL
authInfo
ObjectisProxy
Booleanscheme
Stringhost
Stringport
Integerrealm
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'
Emitted when the gpu process crashes.
Event: 'accessibility-support-changed' macOS Windows
Returns:
event
EventaccessibilitySupportEnabled
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
Exits immediately with exitCode
.
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.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 the current application directory.
app.getPath(name)
name
String
Retrieves 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 theappData
directory appended with your app's name.temp
Temporary directory.exe
The current executable file.module
Thelibchromiumcontent
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
Stringpath
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 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 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 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)
macOS Windows
protocol
String - The name of your protocol, without://
. If you want your app to handleelectron://
links, call this method withelectron
as the parameter.
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.
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)
macOS Windows
protocol
String - The name of your protocol, without://
.
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)
macOS Windows
protocol
String - The name of your protocol, without://
.
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 ofTask
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 specifyprocess.execPath
which opens the current program.arguments
String - The command line arguments whenprogram
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 specifyprocess.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.
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 toNSUserActivity.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 behttp
orhttps
.
Creates an NSUserActivity
and sets it as the current activity. The activity
is eligible for Handoff to another device afterward.
app.getCurrentActivityType()
macOS
Returns 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
Objectcertificate
String - Path for the pkcs12 file.password
String - Passphrase for the certificate.
callback
Functionresult
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 the current value displayed in the counter badge.
app.isUnityRunning()
Linux
Returns whether current desktop environment is Unity launcher.
app.getLoginItemSettings()
macOS Windows
Return an Object with the login item settings of the app.
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.
app.setLoginItemSettings(settings)
macOS Windows
settings
ObjectopenAtLogin
Boolean -true
to open the app at login,false
to remove the app as a login item. Defaults tofalse
.openAsHidden
Boolean -true
to open the app as hidden. Defaults tofalse
. The user can edit this setting from the System Preferences soapp.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.
app.isAccessibilitySupportEnabled()
macOS Windows
Returns a 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])
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)
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 becritical
orinformational
. The default isinformational
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 the badge string of the dock.
app.dock.hide()
macOS
Hides the dock icon.
app.dock.show()
macOS
Shows the dock icon.
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.