The MediaStream.onaddtrack
property is an EventHandler
which specifies a function to be called
when the addtrack
event occurs on a MediaStream
instance.
This happens when a new track of any kind is added to the media stream. This
event is fired when the browser adds a track to the stream (such as when a
RTCPeerConnection
is renegotiated or a stream being captured using
HTMLMediaElement.captureStream()
gets a new set of tracks because the
media element being captured loaded a new source.
The addtrack
event does not get fired when JavaScript code
explicitly adds tracks to the stream (by calling addTrack()
).
Syntax
MediaStream.onaddtrack = eventHandler;
Value
This should be set to a function which you provide that accepts as input a
MediaStreamTrackEvent
object representing the addtrack
event
which has occurred. The MediaStreamTrack
representing the track which was
added is specified in the event's track
property.
Example
This example adds a listener which, when a new track is added to the stream, appends a
new item to a list of tracks; the new item shows the track's kind
("audio"
or "video"
) and label
.
stream.onaddtrack = function(event) {
let trackList = document.getElementById("tracks");
let label = document.createElement("li");
label.innerHTML = event.track.kind + ": " + event.track.label;
trackList.appendChild(label);
};
Specifications
Specification | Status | Comment |
---|---|---|
Media Capture and Streams The definition of 'MediaStream.onaddtrack' in that specification. |
Candidate Recommendation | Initial specification. |
Browser compatibility
BCD tables only load in the browser
See also
- The
addtrack
event and its type,MediaStreamTrackEvent
.