Guide to the Fullscreen API - Web APIs 编辑

This article demonstrates how to use the Fullscreen API to place a given element into full-screen mode, as well as how to detect when the browser enters or exits full-screen mode.

Activating full-screen mode

Given an element that you'd like to present in full-screen mode (such as a <video>, for example), you can present it in full-screen mode by calling its requestFullscreen() method.

Let's consider this <video> element:

<video controls id="myvideo">
  <source src="somevideo.webm"></source>
  <source src="somevideo.mp4"></source>
</video>

We can put that video into full-screen mode as follows:

var elem = document.getElementById("myvideo");
if (elem.requestFullscreen) {
  elem.requestFullscreen();
}

This code checks for the existence of the requestFullscreen() method before calling it.

Presentation differences

It's worth noting a key difference here between the Gecko and WebKit implementations at this time: Gecko automatically adds CSS rules to the element to stretch it to fill the screen: "width: 100%; height: 100%". WebKit doesn't do this; instead, it centers the fullscreen element at the same size in a screen that's otherwise black. To get the same fullscreen behavior in WebKit, you need to add your own "width: 100%; height: 100%;" CSS rules to the element yourself:

#myvideo:-webkit-full-screen {
  width: 100%;
  height: 100%;
}

On the other hand, if you're trying to emulate WebKit's behavior on Gecko, you need to place the element you want to present inside another element, which you'll make fullscreen instead, and use CSS rules to adjust the inner element to match the appearance you want.

Notification

When fullscreen mode is successfully engaged, the document which contains the element receives a fullscreenchange event. When fullscreen mode is exited, the document again receives a  fullscreenchange event. Note that the fullscreenchange event doesn't provide any information itself as to whether the document is entering or exiting fullscreen mode, but if the document has a non null fullscreenElement, you know you're in fullscreen mode.

When a fullscreen request fails

It's not guaranteed that you'll be able to switch into fullscreen mode. For example, <iframe> elements have the allowfullscreen attribute in order to opt-in to allowing their content to be displayed in fullscreen mode. In addition, certain kinds of content, such as windowed plug-ins, cannot be presented in fullscreen mode. Attempting to put an element which can't be displayed in fullscreen mode (or the parent or descendant of such an element) won't work. Instead, the element which requested fullscreen will receive a mozfullscreenerror event. When a fullscreen request fails, Firefox will log an error message to the Web Console explaining why the request failed. In Chrome and newer versions of Opera however, no such warning is generated.

Note: Fullscreen requests need to be called from within an event handler or otherwise they will be denied. 

Getting out of full screen mode

The user always has the ability to exit fullscreen mode of their own accord; see Things your users want to know. You can also do so programmatically by calling the Document.exitFullscreen() method.

Other information

The Document provides some additional information that can be useful when developing fullscreen web applications:

DocumentOrShadowRoot.fullscreenElement

The fullscreenElement property tells you the Element that's currently being displayed fullscreen. If this is non-null, the document is in fullscreen mode. If this is null, the document is not in fullscreen mode.

Document.fullscreenEnabled

The fullscreenEnabled property tells you whether or not the document is currently in a state that would allow fullscreen mode to be requested.

Things your users want to know

You'll want to be sure to let your users know that they can press the Esc key (or F11) to exit fullscreen mode.

In addition, navigating to another page, changing tabs, or switching to another application (using, for example, Alt-Tab) while in fullscreen mode exits fullscreen mode as well.

Example

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

View Live Examples

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

Toggling fullscreen mode

This code is called when the user hits the Enter key, as seen above.

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

This starts by looking at the value of the fullscreenElement attribute on the document (checking it prefixed with both moz, ms, or webkit). If it's null, the document is currently in windowed mode, so we need to switch to fullscreen mode. Switching to fullscreen mode is done by calling element.requestFullscreen().

If fullscreen mode is already active (fullscreenElement is non-null), we call document.exitFullscreen().

Prefixing

Note: Currently, only Firefox 64 and Chrome 71 supports this unprefixed.

For the moment not all browsers are implementing the unprefixed version of the API (for vendor agnostic access to the Fullscreen API you can use Fscreen). Here is the table summarizing the prefixes and name differences between them:

Standard	WebKit (Safari) / Blink (Chrome & Opera) / Edge	Gecko (Firefox)	Internet Explorer
Document.fullscreen	webkitIsFullScreen	mozFullScreen	-
Document.fullscreenEnabled	webkitFullscreenEnabled	mozFullScreenEnabled	msFullscreenEnabled
DocumentOrShadowRoot.fullscreenElement	webkitFullscreenElement	mozFullScreenElement	msFullscreenElement
Document.onfullscreenchange	onwebkitfullscreenchange	onmozfullscreenchange	onmsfullscreenchange
Document.onfullscreenerror	onwebkitfullscreenerror	onmozfullscreenerror	onmsfullscreenerror
Document.exitFullscreen()	webkitExitFullscreen()	mozCancelFullScreen()	msExitFullscreen()
Element.requestFullscreen()	webkitRequestFullscreen()	mozRequestFullScreen()	msRequestFullscreen()

Specifications

Specification	Status	Comment
Fullscreen API	Living Standard	Initial version.

Browser compatibility

Document.fullscreen

BCD tables only load in the browser

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.

See also

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