<!DOCTYPE html>
<meta charset="utf-8">
<title>SharedWorker Fetcher</title>
<script>
  window.addEventListener("message", function (evt) {
    let { url } = evt.data;

    const worker = new SharedWorker(url);

    worker.onerror = (evt) => {
      parent.postMessage({ error: evt.message || "unknown error" }, "*");
    };

    worker.port.addEventListener("message", (evt) => {
      parent.postMessage(evt.data, "*");
    });
    worker.port.start();
  });
</script>
