WebRTC - how to set always to use TURN server?

In the standard specs it says you can set ENUM value to "relay" : http://dev.w3.org/2011/webrtc/editor/webrtc.html#idl-def-RTCIceServer

but, How do you set the enum to "relay" using Javascript of following? if (tmp.indexOf("typ relay ") >= 0) { never occur in my test. how can i force it to enum "relay"?

or

is it a BUG? https://code.google.com/p/webrtc/issues/detail?id=1179

Any idea.

function createPeerConnection() {
  try {
    // Create an RTCPeerConnection via the polyfill (adapter.js).
    pc = new RTCPeerConnection(pcConfig, pcConstraints);
    pc.onicecandidate = onIceCandidate;
    console.log('Created RTCPeerConnnection with:\n' +
                '  config: \'' + JSON.stringify(pcConfig) + '\';\n' +
                '  constraints: \'' + JSON.stringify(pcConstraints) + '\'.');
  } catch (e) {
    console.log('Failed to create PeerConnection, exception: ' + e.message);
    alert('Cannot create RTCPeerConnection object; \
          WebRTC is not supported by this browser.');
      return;
  }
  pc.onaddstream = onRemoteStreamAdded;
  pc.onremovestream = onRemoteStreamRemoved;
  pc.onsignalingstatechange = onSignalingStateChanged;
  pc.oniceconnectionstatechange = onIceConnectionStateChanged;
}

function onIceCandidate(event) {
  if (event.candidate) {
    var tmp = event.candidate.candidate;
    if (tmp.indexOf("typ relay ") >= 0) {
      /////////////////////////////////////////// NEVER happens
      sendMessage({type: 'candidate',
                   label: event.candidate.sdpMLineIndex,
                   id: event.candidate.sdpMid,        
                   candidate: tmp}); 
      noteIceCandidate("Local", iceCandidateType(tmp));   

    }    
  } else {
    console.log('End of candidates.');
  }
}

To force the usage of a TURN server, you need to intercept the candidates found by the browser. Just like you are doing.

But if it never occurs in your testings, you may have some problems with your TURN server. If you have a working TURN server, you'll get the candidates with typ relay.

Remember that you need to configure TURN server with authentication. It is mandatory and the browser will only use the candidates "relay" if the request is authenticated. Your iceServers config for PeerConnection must have the credentials defined for TURN servers.