RTCPeerConnection.canTrickleIceCandidates

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The read-only property RTCPeerConnection.canTrickleIceCandidates returns a Boolean which indicates whether or not the remote peer can accept trickled ICE candidates.

ICE trickling is the process of continuing to send candidates after the initial offer or answer has already been sent to the other peer.

This property is only set after having called RTCPeerConnection.setRemoteDescription().  Ideally, your signaling protocol provides a way to detect trickling support, so that you don't need to rely on this property. A WebRTC browser will always support trickle ICE. If trickling isn't supported, or you aren't able to tell, you can check for a falsy value for this property and then wait until the value of iceGatheringState changes to "completed" before creating and sending the initial offer. That way, the offer contains all of the candidates.

Syntax

 var canTrickle = RTCPeerConnection.canTrickleIceCandidates;

Value

A Boolean that is true if the remote peer can accept trickled ICE candidates and false if it cannot. If no remote peer has been established, this value is null.

This property's value is determined once the local peer has called RTCPeerConnection.setRemoteDescription(); the provided description is used by the ICE agent to determine whether or not the remote peer supports trickled ICE candidates.

Example

var pc = new RTCPeerConnection();
// The following code might be used to handle an offer from a peer when
// it isn't known whether it supports trickle ICE.
pc.setRemoteDescription(remoteOffer)
  .then(_ => pc.createAnswer())
  .then(answer => {
    if (pc.canTrickleIceCandidates) {
      return answer;
    }
    return new Promise(r => {
      pc.addEventListener('icegatheringstatechange', e => {
        if (e.target.iceGatheringState === 'complete') {
          r(answer);
        }
      });
    });
  })
  .then(answer => sendAnswerToPeer(answer)) // signaling message
  .catch(e => handleError(e));

pc.addEventListener('icecandidate', e => {
  if (pc.canTrickleIceCandidates) {
    sendCandidateToPeer(e.candidate); // signaling message
  }
});

Specifications

Specification Status Comment
WebRTC 1.0: Real-time Communication Between Browser
The definition of 'RTCPeerConnection.canTrickleIceCandidates' in that specification.
Working Draft Initial specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) [1] 44 (44) No support (Yes) ?
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? ? 44 (44) No support ? ?

See also

Document Tags and Contributors

 Contributors to this page: m_t, Sheppy, teoli
 Last updated by: m_t,