Guide to the Fullscreen API
This article demonstrates how to use the Fullscreen API to place a given element into fullscreen mode, as well as how to detect when the browser enters or exits fullscreen mode.
Activating fullscreen mode
Given an element that you'd like to present in fullscreen mode (such as a <video>
, for example), you can present it in fullscreen 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 fullscreen mode as follows:
const elem = document.getElementById("myvideo");
if (elem.requestFullscreen) {
elem.requestFullscreen();
}
This code checks for the existence of the requestFullscreen()
method before calling it.
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 fullscreenerror
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:
Document.fullscreenElement
/ShadowRoot.fullscreenElement
-
The
fullscreenElement
property tells you theElement
that's currently being displayed fullscreen. If this is non-null, the document (or shadow DOM) is in fullscreen mode. If this is null, the document (or shadow DOM) 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.
Viewport scaling in mobile browsers
Some mobile browsers while in fullscreen mode ignore viewport meta-tag settings and block user scaling; for example: a "pinch to zoom" gesture may not work on a page presented in fullscreen mode — even if, when not in fullscreen mode, the page can be scaled using pinch to zoom.
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.
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",
(e) => {
if (e.key === "Enter") {
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
. 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()
.
Specifications
Specification |
---|
Fullscreen API Standard # ref-for-dom-document-fullscreenenabled① |
Fullscreen API Standard # dom-document-fullscreen |
Browser compatibility
api.Document.fullscreenEnabled
BCD tables only load in the browser
api.Document.fullscreen
BCD tables only load in the browser