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.

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.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("track", (event) => { })

ontrack = (event) => { }

Event type

An RTCTrackEvent. Inherits from Event.

Examples

This example shows code that creates a new RTCPeerConnection, then adds a new track event handler.

pc = new RTCPeerConnection({
  iceServers: [
    {
      urls: "turn:fake.turn-server.url",
      username: "some username",
      credential: "some-password",
    },
  ],
});

pc.addEventListener("track", (e) => {
  videoElement.srcObject = e.streams[0];
  hangupButton.disabled = 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;
};

Specifications

Browser compatibility