The track
event is sent to the ontrack
event handler on RTCPeerConnection
s after a new track has been added to an RTCRtpReceiver
which is part of the connection.
By the time this event is delivered, the new track has been fully added to the peer connection. See Track event types for details.
This event is not cancellable and does not bubble.
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("track", (event) => {});
ontrack = (event) => {};
Since RTCTrackEvent
is based on Event
, its properties are also available.
-
receiver
Read only
-
The RTCRtpReceiver
used by the track that's been added to the RTCPeerConnection
.
-
streams
Read only Optional
-
An array of MediaStream
objects, each representing one of the media streams to which the added track
belongs. By default, the array is empty, indicating a streamless track.
-
track
Read only
-
The MediaStreamTrack
which has been added to the connection.
-
transceiver
Read only
-
The RTCRtpTransceiver
being used by the new track.
This example shows code that creates a new RTCPeerConnection
, then adds a new track
event handler.
pc = new RTCPeerConnection({
iceServers: [
{
urls: "turn:fake.turnserver.url",
username: "someusername",
credential: "somepassword",
},
],
});
pc.addEventListener(
"track",
(e) => {
videoElement.srcObject = e.streams[0];
hangupButton.disabled = false;
},
false,
);
The event handler assigns the new track's first stream to an existing <video>
element, identified using the variable videoElement
.
You can also assign the event handler function to the ontrack
property, rather than use addEventListener()
.
pc.ontrack = (e) => {
videoElement.srcObject = e.streams[0];
hangupButton.disabled = false;
return false;
};