Experimenting with ways to take JavaScript on the client and make web workers with it.

web_worker_experiment.js

function workerMessageHandler({ data, origin, lastEventId, source, ports }) {
  console.warn(`worker got message
    data: ${JSON.stringify(data)}
    origin: ${origin}
    lastEventId: ${lastEventId}
    source: ${source}
    ports: ${ports}
  `);

  self.addEventListener("message", function(e) {
    postMessage(x * 2); // Intentional error. 'x' is not defined.
  });

  postMessage(`got your message: ${JSON.stringify(data)}`);
}

function aWorker(handler) {
  return `onmessage = ${handler}`;
}

function workerFactory() {
  const workerBlob = new Blob([aWorker(workerMessageHandler)], {
    type: "text/javascript"
  });

  const workerDataUrl = URL.createObjectURL(workerBlob);

  const myWorker = new Worker(workerDataUrl);

  myWorker.onmessage = function({ data, origin, lastEventId, source, ports }) {
    console.log(`message from worker:
      data: ${data}
      origin: ${origin}
      lastEventId: ${lastEventId}
      source: ${source}
      ports: ${ports}
    `);
  };

  myWorker.onerror = function({ lineno, filename, message }) {
    console.error(`ERROR in worker:
      Line: ${lineno}
      In: ${filename}
      Message: ${message}
    `);
  };

  myWorker.postMessage({ type: "example", data: [1, 2, 3, 4] });
  return myWorker;
}

const PeepIt = workerFactory();