function test_workers() {

  onmessage = function(e) {

    postMessage(e.data, e.ports);

  }

}

function test_broadcastChannel() {

  var bc = new BroadcastChannel('postMessagesTest_inWorkers');

  bc.onmessage = function(e) {

    postMessage(e.data);

  }

}

function test_messagePort(port) {

  port.onmessage = function(e) {

    postMessage(e.data, e.ports);

  }

}

onmessage = function(e) {

  if (e.data == 'workers') {

    test_workers();

    postMessage('ok');

  } else if (e.data == 'broadcastChannel') {

    test_broadcastChannel();

    postMessage('ok');

  } else if (e.data == 'messagePort') {

    test_messagePort(e.ports[0]);

    postMessage('ok');

  } else {

    postMessage('ko');

  }

}