electron/docs/api/app.md

# app

The `app` module is responsible for controlling the application's lifecycle.

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

```javascript
var app = require('app');
app.on('window-all-closed', function() {
  app.quit();
});
```

## Events

The following are events on `app`.

### 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 OS X,
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.

This event is only emitted when the application is not going to quit. 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'

* `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'

* `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'

Emitted when the application is quitting.

### Event: 'open-file'

* `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.

### Event: 'open-url'

* `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-with-no-open-windows'

Emitted when the application is activated while there are no open windows, which
usually happens when the user has closed all of the application's windows and then
clicks on the application's dock icon.

### Event: 'browser-window-blur'

* `event` Event
* `window` BrowserWindow

Emitted when a [browserWindow](browser-window.md) gets blurred.

### Event: 'browser-window-focus'

* `event` Event
* `window` BrowserWindow

Emitted when a [browserWindow](browser-window.md) gets focused.

### Event: 'select-certificate'

Emitted when a client certificate is requested.

* `event` Event
* `webContents` [WebContents](browser-window.md#class-webcontents)
* `url` String
* `certificateList` [Objects]
  * `data` PEM encoded data
  * `issuerName` Issuer's Common Name
* `callback` Function

```javascript
app.on('select-certificate', function(event, host, url, list, callback) {
  event.preventDefault();
  callback(list[0]);
})
```

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.

### Event: 'gpu-process-crashed'

Emitted when the gpu process crashes.

## Methods

The following are methods on the `app` class.

### `app.quit()`

Try to close all windows. The `before-quit` event will 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.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
  * `$XDG_CONFIG_HOME` or `~/.config` on Linux
  * `~/Library/Application Support` on OS X
* `userData` The directory for storing your app's configuration files, which by
  default it is the `appData` directory appended with your app's name.
* `cache` Per-user application cache directory, which by default points to:
  * `%APPDATA%` on Windows (which doesn't have a universal cache location)
  * `$XDG_CACHE_HOME` or `~/.cache` on Linux
  * `~/Library/Caches` on OS X
* `userCache` The directory for placing your app's caches, by default it is the
 `cache` directory appended with your app's name.
* `temp` Temporary directory.
* `userDesktop` The current user's Desktop directory.
* `exe` The current executable file.
* `module` The `libchromiumcontent` library.

### `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's 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.resolveProxy(url, callback)`

* `url` URL
* `callback` Function

Resolves the proxy information for `url`. The `callback` will be called with
`callback(proxy)` when the request is performed.

### `app.addRecentDocument(path)`

* `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 OS X you can visit it from dock menu.

### `app.clearRecentDocuments()`

Clears the recent documents list.

### `app.setUserTasks(tasks)`

* `tasks` Array - Array of `Task` objects

Adds `tasks` to the [Tasks][tasks] category of the JumpList on Windows.

`tasks` is an array of `Task` objects in 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.

**Note:** This API is only available on Windows.

### `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])

* `type` String - 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.

**Note:** This API is only available on OS X.

### `app.dock.cancelBounce(id)`

* `id` Integer

Cancel the bounce of `id`.

**Note:** This API is only available on OS X.

### `app.dock.setBadge(text)`

* `text` String

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

**Note:** This API is only available on OS X.

### `app.dock.getBadge()`

Returns the badge string of the dock.

**Note:** This API is only available on OS X.

### `app.dock.hide()`

Hides the dock icon.

**Note:** This API is only available on OS X.

### `app.dock.show()`

Shows the dock icon.

**Note:** This API is only available on OS X.

### `app.dock.setMenu(menu)`

* `menu` Menu

Sets the application's [dock menu][dock-menu].

**Note:** This API is only available on OS X.

[dock-menu]:https://developer.apple.com/library/mac/documentation/Carbon/Conceptual/customizing_docktile/concepts/dockconcepts.html#//apple_ref/doc/uid/TP30000986-CH2-TPXREF103
[tasks]:http://msdn.microsoft.com/en-us/library/windows/desktop/dd378460(v=vs.85).aspx#tasks