Web/API/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 StandardThe definition of 'TexTrackList' in that specification.	Living Standard

Browser compatibility

The compatibility table in 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.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
TextTrackList	Chrome Full support Yes	Edge Full support ≤18	Firefox Full support Yes	IE ?	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android ?	Opera Android Full support Yes	Safari iOS ?	Samsung Internet Android Full support Yes
addTrack event	Chrome Full support Yes	Edge Full support ≤79	Firefox ?	IE ?	Opera ?	Safari ?	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android ?	Opera Android ?	Safari iOS ?	Samsung Internet Android Full support Yes
change event	Chrome Full support Yes	Edge Full support ≤79	Firefox ?	IE ?	Opera ?	Safari ?	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android ?	Opera Android ?	Safari iOS ?	Samsung Internet Android Full support Yes
getTrackById	Chrome Full support Yes	Edge Full support 18	Firefox Full support Yes	IE No support No	Opera ?	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android ?	Opera Android ?	Safari iOS ?	Samsung Internet Android Full support Yes
length	Chrome Full support 44	Edge Full support ≤18	Firefox Full support Yes	IE ?	Opera Full support 31	Safari Full support 10	WebView Android Full support 44	Chrome Android Full support 44	Firefox Android ?	Opera Android Full support 32	Safari iOS ?	Samsung Internet Android Full support 4.0
removeTrack event	Chrome Full support Yes	Edge Full support ≤79	Firefox ?	IE ?	Opera ?	Safari ?	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android ?	Opera Android ?	Safari iOS ?	Samsung Internet Android Full support Yes

Legend

Full support  

Full support

No support  

No support

Compatibility unknown  

Compatibility unknown

TextTrackList by Mozilla Contributors is licensed under CC-BY-SA 2.5.