VideoTrackList

Instance properties

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

length Read only

The number of tracks in the list.

selectedIndex Read only

The index of the currently selected track, if any, or −1 otherwise.

Instance methods

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

getTrackById()

Returns the VideoTrack found within the VideoTrackList whose id matches the specified string. If no match is found, null is returned.

Events

addtrack

Fired when a new video track has been added to the media element. Also available via the onaddtrack property.

change

Fired when a video track has been made active or inactive. Also available via the onchange property.

removetrack

Fired when a new video 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 video tracks present on a media element, VideoTrackList 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.

Examples

Getting a media element's video track list

To get a media element's VideoTrackList, use its videoTracks property.

const videoTracks = document.querySelector("video").videoTracks;

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.

videoTracks.onaddtrack = updateTrackCount;
videoTracks.onremovetrack = updateTrackCount;
function updateTrackCount(event) {
  trackCount = videoTracks.length;
  drawTrackCountIndicator(trackCount);
}

Specifications

Browser compatibility