pc2 onopen fires non-deterministically

gistfile1.js

var RTCPeerConnection = require('wrtc').RTCPeerConnection;
var RTCIceCandidate = require('wrtc').RTCIceCandidate;
var RTCPeerConnectionIceEvent = require('wrtc').RTCPeerConnectionIceEvent;

var pc1 = new RTCPeerConnection(null);
var pc2 = new RTCPeerConnection(null);

var channel = pc1.createDataChannel(null, {});
channel.onopen = function(ev) {
    console.log('open');
};
pc2.ondatachannel = function(ev) {
    console.log('pc2 on data channel');
    ev.channel.onopen = function(ev2) {
        console.log('dc2 open');
        setTimeout(function() {
            pc1.close();
            pc2.close();
        }, 500);
    };
};

function waitForPcGatheringComplete(pc) {
    setTimeout(function() {
        if(pc.iceGatheringState === "complete") {
            pc.onicecandidate(new RTCPeerConnectionIceEvent('icecandidate', {candidate: null}));
        } else {
            waitForPcGatheringComplete(pc);
        }
    }, 100);
}

pc1.createOffer(function(offer) {
    pc1.setLocalDescription(offer);
    pc1.onicecandidate = function(ev) {
        if(pc1.iceGatheringState === "complete" || ev.candidate === null) {
            pc1.onicecandidate = null;
            pc2.setRemoteDescription(pc1.localDescription);
            pc2.createAnswer(function(answer) {
                pc2.setLocalDescription(answer);
                pc2.onicecandidate = function(ev2) {
                    if(pc2.iceGatheringState === "complete" || ev2.candidate === null) {
                        pc2.onicecandidate = null;
                        pc1.setRemoteDescription(pc2.localDescription);
                    }
                };
                waitForPcGatheringComplete(pc2);
            });
        }
    };
    waitForPcGatheringComplete(pc1);
});

Have you looked at the bridge/peer example I wrote? It does basically this. Run bridge.js in node and open peer.html in a browser.