Fullscreen API - Web APIs 编辑

The Fullscreen API adds methods to present a specific Element (and its descendants) in full-screen mode, and to exit full-screen mode once it is no longer needed. This makes it possible to present desired content—such as an online game—using the user's entire screen, removing all browser user interface elements and other applications from the screen until full-screen mode is shut off.

See the article Guide to the Fullscreen API for details on how to use the API.

Note: Support for this API varies somewhat across browsers, with many requiring vendor prefixes and/or not implementing the latest specification. See the Browser compatibility section below for details on support for this API. You may wish to consider using a library such as Fscreen for vendor agnostic access to the Fullscreen API.

Interfaces

The Fullscreen API has no interfaces of its own. Instead, it augments several other interfaces to add the methods, properties, and event handlers needed to provide full-screen functionality. These are listed in the following sections.

Methods

The Fullscreen API adds methods to the Document and Element interfaces to allow turning off and on full-screen mode.

Methods on the Document interface

Document.exitFullscreen()

Requests that the user agent switch from full-screen mode back to windowed mode. Returns a Promise which is resolved once full-screen mode has been completely shut off.

Methods on the Element interface

Element.requestFullscreen()

Asks the user agent to place the specified element (and, by extension, its descendants) into full-screen mode, removing all of the browser's UI elements as well as all other applications from the screen. Returns a Promise which is resolved once full-screen mode has been activated.

Properties

The Document interface provides properties that can be used to determine if full-screen mode is supported and available, and if full-screen mode is currently active, which element is using the screen.

DocumentOrShadowRoot.fullscreenElement

The fullscreenElement property tells you the Element that's currently being displayed in full-screen mode on the DOM (or shadow DOM). If this is null, the document is not in full-screen mode.

document.fullscreenEnabled

The fullscreenEnabled property tells you whether or not it is possible to engage full-screen mode. This is false if full-screen mode is not available for any reason (such as the "fullscreen" feature not being allowed, or full-screen mode not being supported).

Event handlers

The Fullscreen API defines two events which can be used to detect when full-screen mode is turned on and off, as well as when errors occur during the process of changing between full-screen and windowed modes. Event handlers for these events are available on the Document and Element interfaces.

Note: These event handler properties are not available as HTML content attributes. In other words, you cannot specify event handlers for fullscreenchange and fullscreenerror in the HTML content. They must be added by JavaScript code.

Event handlers on documents

Document.onfullscreenchange

An event handler for the fullscreenchange event that's sent to a Document when that document is placed into full-screen mode, or when that document exits full-screen mode. This handler is called only when the entire document is presented in full-screen mode.

Document.onfullscreenerror

An event handler for the fullscreenerror event that gets sent to a Document when an error occurs while trying to enable or disable full-screen mode for the entire document.

Event handlers on elements

Element.onfullscreenchange

An event handler which is called when the fullscreenchange event is sent to the element, indicating that the element has been placed into, or removed from, full-screen mode.

Element.onfullscreenerror

An event handler for the fullscreenerror event when sent to an element which has encountered an error while transitioning into or out of full-screen mode.

Obsolete properties

Document.fullscreen 

A Boolean value which is true if the document has an element currently being displayed in full-screen mode; otherwise, this returns false. Note: Use the fullscreenElement property on the Document or ShadowRoot instead; if it's not null, then it's an Element currently being displayed in full-screen mode.

Events

The Fullscreen API defines two events which can be used to detect when full-screen mode is turned on and off, as well as when errors occur during the process of changing between full-screen and windowed modes.

fullscreenchange

Sent to a Document or Element when it transitions into or out of full-screen mode.

fullscreenerror

Sent to a Document or Element if an error occurs while attempting to switch it into or out of full-screen mode.

Dictionaries

FullscreenOptions

Provides optional settings you can specify when calling requestFullscreen().

Controlling access

The availability of full-screen mode can be controlled using Feature Policy. The full-screen mode feature is identified by the string "fullscreen", with a default allow-list value of "self", meaning that full-screen mode is permitted in top-level document contexts, as well as to nested browsing contexts loaded from the same origin as the top-most document.

See Using Feature Policy to learn more about using Feature Policy to control access to an API.

Usage notes

Users can choose to exit full-screen mode by pressing the ESC (or F11) key, rather than waiting for the site or app to programmatically do so. Make sure you provide, somewhere in your user interface, appropriate user interface elements that inform the user that this option is available to them.

Note: Navigating to another page, changing tabs, or switching to another application using any application switcher (or Alt-Tab) will likewise exit full-screen mode.

Examples

Simple fullscreen usage

In this example, a video is presented in a web page. Pressing the Enter key lets the user toggle between windowed and full-screen presentation of the video.

View Live Example

Watching for the Enter key

When the page is loaded, this code is run to set up an event listener to watch for the Enter key.

document.addEventListener("keypress", function(e) {
  if (e.keyCode === 13) {
    toggleFullScreen();
  }
}, false);

Toggling full-screen mode

This code is called by the event handler above when the user hits the Enter key.

function toggleFullScreen() {
  if (!document.fullscreenElement) {
      document.documentElement.requestFullscreen();
  } else {
    if (document.exitFullscreen) {
      document.exitFullscreen();
    }
  }
}

This starts by looking at the value of the document's fullscreenElement attribute. In a real-world deployment, at this time, you'll want to check for prefixed versions of this (mozFullScreenElement, msFullscreenElement, or webkitFullscreenElement, for example). If the value is null, the document is currently in windowed mode, so we need to switch to full-screen mode; otherwise, it's the element that's currently in full-screen mode. Switching to full-screen mode is done by calling Element.requestFullscreen() on the <video> element.

If full-screen mode is already active (fullscreenElement is not null), we call exitFullscreen() on the document to shut off full-screen mode.

Specifications

Specification	Status
Fullscreen API	Living Standard

Browser compatibility

Document.fullscreen

BCD tables only load in the browser

Document.fullscreenElement

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Document.fullscreenEnabled

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Document.exitFullscreen

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Element.requestFullscreen

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

See also

• Using full-screen mode
• Element.requestFullscreen()
• Document.exitFullscreen()
• Document.fullscreen
• Document.fullscreenElement
• :fullscreen, ::backdrop
• allowfullscreen