TextTrackList

The TextTrackList interface is used to represent a list of the text tracks defined by the <track> element, with each track represented by a separate textTrack object in the list.

Retrieve an instance of this object with HTMLMediaElement.textTracks. The individual tracks can be accessed using array syntax or functions such as forEach() for example.

Properties

This interface also inherits properties from its parent interface, EventTarget.

length Read only
The number of tracks in the list.

Event handlers

onaddtrack
An event handler to be called when the addtrack event is fired, indicating that a new text track has been added to the media element.
onchange
An event handler to be called when the change event occurs.
onremovetrack
An event handler to call when the removetrack event is sent, indicating that a text track has been removed from the media element.

Methods

This interface also inherits methods from its parent interface, EventTarget.

getTrackById()
Returns the TextTrack found within the TextTrackList whose id matches the specified string. If no match is found, null is returned.

Events

addtrack
Fired when a new text track has been added to the media element.
Also available via the onaddtrack property.
change
Fired when a text track has been made active or inactive.
Also available via the onchange property.
removetrack
Fired when a new text track has been removed from the media element.
Also available via the onremovetrack property.

Usage notes

In addition to being able to obtain direct access to the text tracks present on a media element, TextTrackList lets you set event handlers on the addtrack and removetrack events, so that you can detect when tracks are added to or removed from the media element's stream. See onaddtrack and onremovetrack for details and examples.

Examples

Getting a video element's text track list

To get a media element's TextTrackList, use its textTracks property.

var textTracks = document.querySelector("video").textTracks;

Monitoring track count changes

In this example, we have an app that displays information about the number of channels available. To keep it up to date, handlers for the addtrack and removetrack events are set up.

textTracks.onaddtrack = updateTrackCount;
textTracks.onremovetrack = updateTrackCount;

function updateTrackCount(event) {
  trackCount = textTracks.length;
  drawTrackCountIndicator(trackCount);
}

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'TexTrackList' in that specification.
Living Standard  

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
TextTrackListChrome Full support YesEdge Full support YesFirefox Full support YesIE ? Opera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android Full support YesSafari iOS ? Samsung Internet Android Full support Yes
addTrack eventChrome Full support YesEdge ? Firefox ? IE ? Opera ? Safari ? WebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android ?
change eventChrome Full support YesEdge ? Firefox ? IE ? Opera ? Safari ? WebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android ?
getTrackByIdChrome Full support YesEdge Full support 18Firefox Full support YesIE ? Opera ? Safari Full support 6WebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android Full support Yes
lengthChrome Full support 44Edge Full support YesFirefox Full support YesIE ? Opera Full support 31Safari Full support 10WebView Android Full support 44Chrome Android Full support 44Firefox Android ? Opera Android Full support 32Safari iOS ? Samsung Internet Android Full support Yes
removeTrack eventChrome Full support YesEdge ? Firefox ? IE ? Opera ? Safari ? WebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown