function data(pc, opener) {
  if (opener) {
    config(pc.createDataChannel("work"));
  } else {
    pc.ondatachannel = function(evt) {
      config(evt.channel);
    }
  }
}

function config(channel) {
  channel.onmessage = function(evt) {
    console.log(evt.data);
    channel.send("received message");
  }
}