<!DOCTYPE HTML>
<html>
<body>
  <script type="application/javascript">

  function ok(what, msg) {
    window.parent.postMessage({type: what ? 'OK' : 'KO', msg }, '*');
  }

  window.addEventListener('message', receiveMessage);
  function receiveMessage(evt) {
    ok(evt.ports.length == 1, "Port transferred!");

    var a = new MessageChannel();
    ok(a, "MessageChannel created");
    evt.ports[0].postMessage('hello world!', [a.port2]);
    a.port1.onmessage = function(event) {
      event.target.postMessage(event.data);
    }
  }

  </script>
</body>
</html>
