Window Management API

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The Window Management API allows you to get detailed information on the displays connected to your device and more easily place windows on specific screens, paving the way towards more effective multi-screen applications.

Concepts and usage

Historically, we have used Window.open() to manage browser windows related to the current application — opening new windows, resizing and closing existing windows, etc. For example, to open a 400×300 window 50 pixels from the left and top of your screen:

js
const myWindow = window.open(
  "https://example.com/",
  "myWindow",
  "left=50,top=50,width=400,height=300",
);

You can retrieve information about your screen from the Window.screen property, such as how much screen space you have available to place windows in.

However, the above features are limited. Window.screen only returns data about the primary screen, and not secondary displays available to a device. To move a window to a secondary display, you could use Window.moveTo(), but you'd have to guess what coordinates to use based on where it is placed in your setup relative to the primary display.

The Window Management API provides more robust, flexible window management. It allows you to query whether your display is extended with multiple screens and get information on each screen separately: windows can then be placed on each screen as desired. It also provides event handlers to allow you to respond to changes in the available screens, new fullscreen functionality to choose which screen to put into fullscreen mode (if any), and permissions functionality to control access to the API.

For details on how to use it, see Using the Window Management API.

Note: In modern browsers, a separate user gesture event is required for each Window.open() call, for security purposes. This prevents sites from spamming users with lots of windows. However, this poses an issue for multi-window applications. To work around this limitation, you can design your applications to open no more than one new window at once, reuse existing windows to display different pages, or advise users on how to update their browser settings to allow multiple windows.

Use cases

The Window Management API is useful in cases such as:

Multi-window graphics editors and audio processors that may wish to arrange editing tools and panels across different screens.
Virtual trading desks that want to show market trends in multiple windows and put specific windows of interest in fullscreen mode.
Slideshow apps that want to show speaker notes on the internal primary screen and the presentation on an external projector.

Permissions policy integration

The window-management Permissions-Policy can be used to control permission to use the Window Management API. Specifically:

Usage of the Window.getScreenDetails() method. If blocked, its Promise will reject with a NotAllowedError exception.
Querying the Window.screen.isExtended property. If blocked, it will always return false.

Developers can explicitly grant permission for an <iframe> to use Window Management via the allow attribute:

html