gecko-dev/dom/broadcastchannel/tests/broadcastchannel_worker.js

onmessage = function(evt) {
  if (evt.data != 0) {
    var worker = new Worker("broadcastchannel_worker.js");
    worker.onmessage = function(event) {
      postMessage(event.data);
    };
    worker.postMessage(evt.data - 1);
    return;
  }

  var bc = new BroadcastChannel("foobar");
  bc.addEventListener("message", function(event) {
    bc.postMessage(
      event.data == "hello world from the window"
        ? "hello world from the worker"
        : "KO"
    );
    bc.close();
  });

  postMessage("READY");
};