The obsolete addstream event is sent to an RTCPeerConnection when new media, in the form of a MediaStream object, has been added to it.

You can, similarly, watch for streams to be removed from the connection by monitoring the removestream event.

This event is not cancelable and does not bubble.

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

addEventListener("addstream", (event) => {});

onaddstream = (event) => {};

A MediaStreamEvent. Inherits from Event.

A MediaStreamEvent being an Event, this event also implements these properties.

MediaStreamEvent.stream Read only

Contains the MediaStream containing the stream associated with the event.

This example looks to determine if the user's browser supports the track event. If it does, a track event listener is set up; otherwise, an addstream event listener is set up. pc is an RTCPeerConnection.

if (pc.addTrack !== undefined) {
  pc.ontrack = (ev) => {
    ev.streams.forEach((stream) => doAddStream(stream));
  };
} else {
  pc.onaddstream = (ev) => {
    doAddStream(ev.stream);
  };
}

This calls a function doAddStream() once for each stream being added to the RTCPeerConnection, regardless of whether the browser sends addstream or track.

You can also use the addEventListener() method to set an event listener:

pc.addEventListener("addstream", (ev) => doAddStream(ev.stream), false);

• WebRTC API
• RTCPeerConnection.addStream()
• MediaStreamEvent