RTCPeerConnection: track event

The track event is sent to the ontrack event handler on RTCPeerConnections after a new track has been added to an RTCRtpReceiver which is part of the connection.

Bubbles Yes
Cancelable No
Interface RTCTrackEvent
Event handler property ontrack

By the time this event is delivered, the new track has been fully added to the peer connection. See Track event types in RTCTrackEvent for details.


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;


WebRTC 1.0: Real-Time Communication Between Browsers (WebRTC 1.0)
# event-track

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