Web/API/AudioTrackList/onaddtrack

The AudioTrackList property onaddtrack is an event handler which is called when the addtrack event occurs, indicating that a new audio track has been added to the media element whose audio tracks the AudioTrackList represents.

The event is passed into the event handler in the form of a TrackEvent object, whose track property identifies the newly-added track.

Note: You can also add a handler for the addtrack event using addEventListener().

Syntax

AudioTrackList.onaddtrack = eventHandler;

Value

Set onaddtrack to a function that accepts as input a TrackEvent object which indicates in its track property which audio track has been added to the media.

Usage notes

The addtrack event is called whenever a new track is added to the media element whose audio tracks are represented by the AudioTrackList object. This happens when tracks are added to the element when the media is first attached to the element; one addtrack event will occur for each audio track in the media resource.

Example

This snippet establishes a handler for the addtrack event that calls a function, addToTrackList(), passing in the AudioTrack object representing the newly-added track. In this scenario, that function's role is to add the new track to a list of audio tracks available to choose from.

document.querySelector("video").audioTracks.onaddtrack = function(event) {
  addToTrackList(event.track);
};

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'AudioTrackList.onaddtrack' in that specification.	Living Standard
HTML5The definition of 'AudioTrackList.onaddtrack' in that specification.	Recommendation

Browser compatibility

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
`onaddtrack`	Chrome Full support 37 Disabled' Full support 37 Disabled' Disabled' From version 37: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). To change preferences in Chrome, visit chrome://flags.	Edge Full support 79 Disabled' Full support 79 Disabled' Disabled' From version 79: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). No support 12 — 79	Firefox Full support 33 Disabled' Full support 33 Disabled' Disabled' From version 33: this feature is behind the `media.track.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE Full support 10	Opera Full support 24 Disabled' Full support 24 Disabled' Disabled' From version 24: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`).	Safari Full support 6.1	WebView Android No support No	Chrome Android Full support 37 Disabled' Full support 37 Disabled' Disabled' From version 37: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). To change preferences in Chrome, visit chrome://flags.	Firefox Android Full support 33 Disabled' Full support 33 Disabled' Disabled' From version 33: this feature is behind the `media.track.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 24 Disabled' Full support 24 Disabled' Disabled' From version 24: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`).	Safari iOS Full support 7	Samsung Internet Android No support No

Legend

Full support: Full support
No support: No support
User must explicitly enable this feature.': User must explicitly enable this feature.

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