Interface MediaTrackEventMap

The events fired by a MediaTrack.

interface MediaTrackEventMap {
    activequalitychanged: QualityEvent<"activequalitychanged">;
    change: TrackChangeEvent;
    qualityunavailable: QualityEvent<"qualityunavailable">;
    targetqualitychanged: TargetQualityChangedEvent;
    update: TrackUpdateEvent;

Hierarchy (view full)


activequalitychanged: QualityEvent<"activequalitychanged">

Fired when the media track's active quality changes.

Fired when a media track's enabled or a text track's mode changes.

qualityunavailable: QualityEvent<"qualityunavailable">

Fired when a quality of the track becomes unavailable.


- A Quality can become unavailable due to a DRM restriction (e.g. HDCP).

targetqualitychanged: TargetQualityChangedEvent

Fired when the media track's target quality changes.

Fired when the track updates.


- A track might update because a change propagated from a remote player (e.g. Chromecast).