trisquel-icecat/icecat/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js

new BroadcastChannel("foobar").addEventListener("message", function (event) {
  if (event.data != "READY") {
    event.target.postMessage(event.data);
  }
});

new BroadcastChannel("foobar").postMessage("READY");