gecko-dev/dom/websocket/tests/websocket_basic_worker.js

onmessage = function(event) {
  if (event.data != 0) {
    var worker = new Worker("websocket_basic_worker.js");
    worker.onmessage = function(e) {
      postMessage(e.data);
    };

    worker.postMessage(event.data - 1);
    return;
  }

  status = false;
  try {
    if (WebSocket instanceof Object) {
      status = true;
    }
  } catch (e) {}

  postMessage({
    type: "status",
    status,
    msg: "WebSocket object:" + WebSocket,
  });

  var ws = new WebSocket(
    "ws://mochi.test:8888/tests/dom/websocket/tests/file_websocket_hello"
  );
  ws.onopen = function(e) {
    postMessage({ type: "status", status: true, msg: "OnOpen called" });
    ws.send("data");
  };

  ws.onclose = function(e) {};

  ws.onerror = function(e) {
    postMessage({ type: "status", status: false, msg: "onerror called!" });
  };

  ws.onmessage = function(e) {
    postMessage({
      type: "status",
      status: e.data == "Hello world!",
      msg: "Wrong data",
    });
    ws.close();
    postMessage({ type: "finish" });
  };
};