AudioTrackList

The AudioTrackList interface is used to represent a list of the audio tracks contained within a given HTML media element, with each track represented by a separate AudioTrack object in the list.

The individual tracks can be accessed using array syntax or functions such as forEach().

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 audio track has been added to the media element.
onchange
An event handler to be called hwen the change event occurs. This occurs when one or more tracks have been enabled or disabled by their enabled flag being changed.
onremovetrack
An event handler to call when the removetrack event is sent, indicating that an audio track has been removed from the media element.

Methods

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

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

Usage notes

In addition to being able to obtain direct access to the audio tracks present on a media element, AudioTrackList 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 media element's audio track list

To get a media element's AudioTrackList, use its audioTracks property.

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

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.

audioTracks.onaddtrack = updateTrackCount;
audioTracks.onremovetrack = updateTrackCount;

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

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'AudioTrackList' in that specification.
Living Standard  
HTML5
The definition of 'AudioTrackList' in that specification.
Recommendation  

Browser compatibility

No compatibility data found. Please contribute data for "api.AudioTrackList" (depth: 1) to the MDN compatibility data repository.

Document Tags and Contributors

Contributors to this page: Sheppy
Last updated by: Sheppy,