var port;
onconnect = function(evt) {
  evt.source.postMessage({ type: "connected" });

  if (!port) {
    port = evt.source;
    evt.source.onmessage = function(evtFromPort) {
      port.postMessage({
        type: "status",
        test: "Port from the main-thread!" == evtFromPort.data,
        msg: "The message is coming from the main-thread",
      });
      port.postMessage({
        type: "status",
        test: evtFromPort.ports.length == 1,
        msg: "1 port transferred",
      });

      evtFromPort.ports[0].onmessage = function(evtFromPort2) {
        port.postMessage({
          type: "status",
          test: evtFromPort2.data.type == "connected",
          msg: "The original message received",
        });
        port.postMessage({ type: "finish" });
        close();
      };
    };
  }
};