electron/docs/api/browser-window.md

browser-window

The BrowserWindow class gives you ability to create a browser window, an example is:

var BrowserWindow = require('browser-window');

var win = new BrowserWindow({ width: 800, height: 600, show: false });
win.on('closed', function() {
  win = null;
});

win.loadUrl('https://github.com');
win.show();

You can also create a window without chrome by using Frameless Window API.

Class: BrowserWindow

BrowserWindow is an EventEmitter.

new BrowserWindow(options)

• options Object
  • x Integer - Window's left offset to screen
  • y Integer - Window's top offset to screen
  • width Integer - Window's width
  • height Integer - Window's height
  • use-content-size Boolean - 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.
  • center Boolean - Show window in the center of the screen
  • min-width Integer - Minimum width
  • min-height Integer - Minimum height
  • max-width Integer - Maximum width
  • max-height Integer - Maximum height
  • resizable Boolean - Whether window is resizable
  • always-on-top Boolean - Whether the window should always stay on top of other windows
  • fullscreen Boolean - Whether the window should show in fullscreen, when set to false the fullscreen button would also be hidden on OS X
  • skip-taskbar Boolean - Do not show window in taskbar
  • zoom-factor Number - The default zoom factor of the page, zoom factor is zoom percent / 100, so 3.0 represents 300%
  • kiosk Boolean - The kiosk mode
  • title String - Default window title
  • icon Image - The window icon
  • show Boolean - Whether window should be shown when created
  • frame Boolean - Specify false to create a Frameless Window
  • node-integration Boolean - Whether node integration is enabled, default is true
  • accept-first-mouse Boolean - Whether the web view accepts a single mouse-down event that simultaneously activates the window
  • auto-hide-menu-bar Boolean - Auto hide the menu bar unless the Alt key is pressed.
  • enable-larger-than-screen Boolean - Enable the window to be resized larger than screen.
  • dark-theme Boolean - Forces using dark theme for the window, only works on some GTK+3 desktop environments
  • preload String - Specifies a script that will be loaded before other scripts run in the window. This script will always have access to node APIs no matter whether node integration is turned on for the window, and the path of preload script has to be absolute path.
  • web-preferences Object - Settings of web page's features
    • javascript Boolean
    • web-security Boolean
    • images Boolean
    • java Boolean
    • text-areas-are-resizable Boolean
    • webgl Boolean
    • webaudio Boolean
    • plugins Boolean - Whether plugins should be enabled, currently only NPAPI plugins are supported.
    • extra-plugin-dirs Array - Array of paths that would be searched for plugins. Note that if you want to add a directory under your app, you should use __dirname or process.resourcesPath to join the paths to make them absolute, using relative paths would make atom-shell search under current working directory.
    • experimental-features Boolean
    • experimental-canvas-features Boolean
    • subpixel-font-scaling Boolean
    • overlay-scrollbars Boolean
    • overlay-fullscreen-video Boolean
    • shared-worker Boolean
    • direct-write Boolean - Whether the DirectWrite font rendering system on Windows is enabled

Creates a new BrowserWindow with native properties set by the options. Usually you only need to set the width and height, other properties will have decent default values.

Event: 'page-title-updated'

• event Event

Emitted when the document changed its title, calling event.preventDefault() would prevent the native window's title to change.

Event: 'close'

• event Event

Emitted when the window is going to be closed. It's emitted before the beforeunload and unload event of DOM, calling event.preventDefault() would 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 atom-shell, returning an empty string or false would cancel the close. An example is:

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

  // Unlike usual browsers, in which a string should be returned and the user is
  // prompted to confirm the page unload. atom-shell gives the power completely
  // to the developers, return empty string or false would prevent the unloading
  // now. You can also use the dialog API to let user confirm it.
  return false;
};

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 anymore.

Event: 'unresponsive'

Emitted when the web page becomes unresponsive.

Event: 'responsive'

Emitted when the unresponsive web page becomes responsive again.

Event: 'blur'

Emitted when window loses focus.

Event: 'focus'

Emitted when window gains focus.

Event: 'maximize'

Emitted when window is maximized.

Event: 'unmaximize'

Emitted when window exits from maximized state.

Event: 'minimize'

Emitted when window is minimized.

Event: 'restore'

Emitted when window is restored from minimized state.

Event: 'enter-full-screen'

Emitted when window enters full screen state.

Event: 'leave-full-screen'

Emitted when window leaves full screen state.

Event: 'devtools-opened'

Emitted when devtools is opened.

Event: 'devtools-closed'

Emitted when devtools is closed.

Class Method: BrowserWindow.getAllWindows()

Returns an array of all opened browser windows.

Class Method: BrowserWindow.getFocusedWindow()

Returns the window that is focused in this application.

Class Method: BrowserWindow.fromWebContents(webContents)

• webContents WebContents

Find a window according to the webContents it owns

Class Method: BrowserWindow.fromId(id)

• id Integer

Find a window according to its ID.

Class Method: 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.

Class Method: BrowserWindow.removeDevToolsExtension(name)

• name String

Remove the devtools extension whose name is name.

BrowserWindow.webContents

The WebContents object this window owns, all web page related events and operations would be done via it.

Note: Users should never store this object because it may becomes null when the web page has crashed.

BrowserWindow.devToolsWebContents

Get the WebContents of devtools of this window.

Note: Users should never store this object because it may becomes null when the devtools has been closed.

BrowserWindow.id

Get the unique ID of this window.

BrowserWindow.destroy()

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

You should only use this method when the web page has crashed.

BrowserWindow.close()

Try to close the window, this has the same effect with user manually clicking the close button of the window. The web page may cancel the close though, see the close event.

BrowserWindow.focus()

Focus on the window.

BrowserWindow.isFocused()

Returns whether the window is focused.

BrowserWindow.show()

Shows and gives focus to the window.

BrowserWindow.showInactive()

Shows the window but doesn't focus on it.

BrowserWindow.hide()

Hides the window.

BrowserWindow.isVisible()

Returns whether the window is visible to the user.

BrowserWindow.maximize()

Maximizes the window.

BrowserWindow.unmaximize()

Unmaximizes the window.

BrowserWindow.isMaximized()

Returns whether the window is maximized.

BrowserWindow.minimize()

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

BrowserWindow.restore()

Restores the window from minimized state to its previous state.

BrowserWindow.isMinimized()

Returns whether the window is minimized.

BrowserWindow.setFullScreen(flag)

• flag Boolean

Sets whether the window should be in fullscreen mode.

BrowserWindow.isFullScreen()

Returns whether the window is in fullscreen mode.

BrowserWindow.setSize(width, height)

• width Integer
• height Integer

Resizes the window to width and height.

BrowserWindow.getSize()

Returns an array that contains window's width and height.

BrowserWindow.setContentSize(width, height)

• width Integer
• height Integer

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

BrowserWindow.getContentSize()

Returns an array that contains window's client area's width and height.

BrowserWindow.setMinimumSize(width, height)

• width Integer
• height Integer

Sets the minimum size of window to width and height.

BrowserWindow.getMinimumSize()

Returns an array that contains window's minimum width and height.

BrowserWindow.setMaximumSize(width, height)

• width Integer
• height Integer

Sets the maximum size of window to width and height.

BrowserWindow.getMaximumSize()

Returns an array that contains window's maximum width and height.

BrowserWindow.setResizable(resizable)

• resizable Boolean

Sets whether the window can be manually resized by user.

BrowserWindow.isResizable()

Returns whether the window can be manually resized by user.

BrowserWindow.setAlwaysOnTop(flag)

• flag Boolean

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.

BrowserWindow.isAlwaysOnTop()

Returns whether the window is always on top of other windows.

BrowserWindow.center()

Moves window to the center of the screen.

BrowserWindow.setPosition(x, y)

• x Integer
• y Integer

Moves window to x and y.

BrowserWindow.getPosition()

Returns an array that contains window's current position.

BrowserWindow.setTitle(title)

• title String

Changes the title of native window to title.

BrowserWindow.getTitle()

Returns the title of the native window.

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

BrowserWindow.flashFrame(flag)

• flag Boolean

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

BrowserWindow.setSkipTaskbar(skip)

• skip Boolean

Makes the window do not show in taskbar.

BrowserWindow.setKiosk(flag)

• flag Boolean

Enters or leaves the kiosk mode.

BrowserWindow.isKiosk()

Returns whether the window is in kiosk mode.

BrowserWindow.setRepresentedFilename(filename)

• filename String

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

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

BrowserWindow.getRepresentedFilename()

Returns the pathname of the file the window represents.

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

BrowserWindow.setDocumentEdited(edited)

• edited Boolean

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

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

BrowserWindow.IsDocumentEdited()

Whether the window's document has been edited.

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

BrowserWindow.openDevTools()

Opens the developer tools.

BrowserWindow.closeDevTools()

Closes the developer tools.

BrowserWindow.toggleDevTools()

Toggle the developer tools.

BrowserWindow.inspectElement(x, y)

• x Integer
• y Integer

Starts inspecting element at position (x, y).

BrowserWindow.focusOnWebView()

BrowserWindow.blurWebView()

BrowserWindow.capturePage([rect, ]callback)

• rect Object - The area of page to be captured
  • x Integer
  • y Integer
  • width Integer
  • height Integer
• callback Function

Captures the snapshot of page within rect, upon completion callback would be called with callback(image), the image is a Buffer that stores the PNG encoded data of the snapshot. Omitting the rect would capture the whole visible page.

You can write received image directly to a .png file, or you can base64 encode it and use data URL to embed the image in HTML.

Note: Be sure to read documents on remote buffer in remote if you are going to use this API in renderer process.

BrowserWindow.print([options])

• options Object
  • silent Boolean - Don't ask user for print settings, defaults to false
  • printBackground Boolean - Also prints the background color and image of the web page, defaults to false.

Prints window's web page. When silent is set to false, atom-shell will pick up system's default printer and default settings for printing.

Calling window.print() in web page is equivalent to call BrowserWindow.print({silent: false, printBackground: false}).

BrowserWindow.loadUrl(url)

Same with webContents.loadUrl(url).

BrowserWindow.reload()

Same with webContents.reload.

BrowserWindow.setMenu(menu)

• menu Menu

Sets the menu as the window top menu.

Note: This API is not available on OS X.

BrowserWindow.setProgressBar(progress)

• progress Double

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.

BrowserWindow.showDefinitionForSelection()

Shows pop-up dictionary that searches the selected word on the page.

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

BrowserWindow.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.

BrowserWindow.isMenuBarAutoHide()

Returns whether menu bar automatically hides itself.

BrowserWindow.setMenuBarVisibility(visible)

• 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.

BrowserWindow.isMenuBarVisible()

Returns whether the menu bar is visible.

Class: WebContents

A WebContents is responsible for rendering and controlling a web page.

WebContents is an EventEmitter.

Event: 'did-finish-load'

Emitted when the navigation is done, i.e. the spinner of the tab will stop spinning, and the onload event was dispatched.

Event: 'did-fail-load'

• event Event
• errorCode Integer
• errorDescription String

This event is like did-finish-load, but emitted when the load failed or was cancelled, e.g. window.stop() is invoked.

Event: 'did-frame-finish-load'

• event Event
• isMainFrame Boolean

Emitted when a frame has done navigation.

Event: 'did-start-loading'

Corresponds to the points in time when the spinner of the tab starts spinning.

Event: 'did-stop-loading'

Corresponds to the points in time when the spinner of the tab stops spinning.

Event: 'did-get-redirect-request'

• event Event
• oldUrl String
• newUrl String
• isMainFrame Boolean

Emitted when a redirect was received while requesting a resource.

Event: 'new-window'

• event Event
• url String
• frameName String
• disposition String - Can be default, foreground-tab, background-tab, new-window and other

Emitted when the page requested to open a new window for url. It could be requested by window.open or an external link like <a target='_blank'>.

By default a new BrowserWindow will be created for the url, and a proxy will be returned to window.open to let you have limited control of it.

Calling event.preventDefault() can prevent creating new windows.

Event: 'will-naviagte'

• event Event
• url String

Emitted when user or the page wants to start an navigation, it can happen when window.location object is changed or user clicks a link in the page.

This event will not emit when the navigation is started programmely with APIs like WebContents.loadUrl and WebContents.back.

Calling event.preventDefault() can prevent the navigation.

Event: 'crashed'

Emitted when the renderer process is crashed.

Event: 'destroyed'

Emitted when the WebContents is destroyed.

WebContents.loadUrl(url)

• url URL

Loads the url in the window, the url must contains the protocol prefix, e.g. the http:// or file://.

WebContents.getUrl()

Returns URL of current web page.

WebContents.getTitle()

Returns the title of web page.

WebContents.isLoading()

Returns whether web page is still loading resources.

WebContents.isWaitingForResponse()

Returns whether web page is waiting for a first-response for the main resource of the page.

WebContents.stop()

Stops any pending navigation.

WebContents.reload()

Reloads current page.

WebContents.reloadIgnoringCache()

Reloads current page and ignores cache.

WebContents.canGoBack()

Returns whether the web page can go back.

WebContents.canGoForward()

Returns whether the web page can go forward.

WebContents.canGoToOffset(offset)

• offset Integer

Returns whether the web page can go to offset.

WebContents.goBack()

Makes the web page go back.

WebContents.goForward()

Makes the web page go forward.

WebContents.goToIndex(index)

• index Integer

Navigates to the specified absolute index.

WebContents.goToOffset(offset)

• offset Integer

Navigates to the specified offset from the "current entry".

WebContents.isCrashed()

Whether the renderer process has crashed.

WebContents.setUserAgent(userAgent)

• userAgent String

Overrides the user agent for this page.

WebContents.insertCSS(css)

• css String

Injects CSS into this page.

WebContents.executeJavaScript(code)

• code String

Evaluate code in page.

WebContents.send(channel[, args...])

• channel String

Send args.. to the web page via channel in asynchronous message, the web page can handle it by listening to the channel event of ipc module.

An example of sending messages from browser side to web pages:

// On browser side.
var window = null;
app.on('ready', function() {
  window = new BrowserWindow({width: 800, height: 600});
  window.loadUrl('file://' + __dirname + '/index.html');
  window.webContents.on('did-finish-load', function() {
    window.webContents.send('ping', 'whoooooooh!');
  });
});

// index.html
<html>
<body>
  <script>
    require('ipc').on('ping', function(message) {
      console.log(message);  // Prints "whoooooooh!"
    });
  </script>
</body>
</html>

Note:

1. The IPC message handler in web pages do not have a event parameter, which is different from the handlers on browser side.
2. There is no way to send synchronous messages from browser side to web pages, because it would be very easy to cause dead locks.