let local_peer = new RTCPeerConnection()
let channel = local_peer.createDataChannel("channel");

channel.onopen = handleSendChannelStatusChange;
channel.onclose = handleSendChannelStatusChange;

let remote_peer = new RTCPeerConnection();

remote_peer.ondatachannel = function(event) {
  let receive_channel = event.channel;
  receive_channel.onmessage = event => console.log(event);
  receive_channel.onopen = function() { console.log("Receive channel has been opened!") };
  receive_channel.onclose = function() { console.log("Receive channel has been closed!") };
};

local_peer.onicecandidate = function(event) {
  remote_peer.addIceCandidate(event.candidate);
}

remote_peer.onicecandidate = e => !e.candidate || local_peer.addIceCandidate(e.candidate);

local_peer.createOffer()
  .then(offer => local_peer.setLocalDescription(offer))
  .then(() => remote_peer.setRemoteDescription(local_peer.localDescription))
  .then(() => remote_peer.createAnswer())
  .then(answer => remote_peer.setLocalDescription(answer))
  .then(() => local_peer.setRemoteDescription(remote_peer.localDescription));

function handleSendChannelStatusChange(event) {
  if (channel.readyState === "open") {
    console.log("Open!")
  } else {
    console.log("Not open!")
  }

  channel.send("hello!")
}