RTCIceTransport: gatheringstatechange event

A gatheringstatechange event is sent to an RTCIceTransport when its ICE candidate gathering state changes. The gathering state, whose actual status can be found in the transport object's gatheringState property, indicates whether or not the ICE agent has begun gathering candidates, and if so, if it has finished doing so.

The key difference between gatheringstatechange and icegatheringstatechange is that the latter represents the overall state of the connection including every RTCIceTransport used by every RTCRtpSender and every RTCRtpReceiver on the entire connection. In contrast, gatheringstatechange represents changes to the candidate gathering state for a single transport.

Examples

This example creates a handler for gatheringstatechange events on each RTCRtpSender associated with a given RTCPeerConnection. Here, the addEventListener() method is called to add a listener for gatheringstatechange events:

pc.getSenders().forEach(sender => {
  sender.transport.iceTransport.addEventListener("gatheringstatechange", ev => {
  let transport = ev.target;

  if (transport.gatheringState === "complete") {
    /* this transport has finished gathering candidates,
       but others may still be working on it */
  }
}, false);

Likewise, you can use the ongatheringstatechange event handler property:

pc.getSenders().forEach(sender => {
  sender.transport.iceTransport.ongatheringstatechange = ev => {
    let transport = ev.target;

    if (transport.gatheringState === "complete") {
      /* this transport has finished gathering candidates,
         but others may still be working on it */
    }
  };
});

Specifications

Browser compatibility

See also

• WebRTC API
• WebRTC connectivity
• RTCIceTransport.ongatheringstatechange

Related RTCIceTransport events

• statechange
• selectedcandidatepairchange

Related RTCPeerConnection events

• negotiationneeded
• signalingstatechange
• iceconnectionstatechange
• icegatheringstatechange
• connectionstatechange