<!DOCTYPE html>
<title>Iframe for Shared Worker: Data URL cross-origin checks</title>
<body>
<script>

let worker = new SharedWorker('data:text/javascript,let conns=0; onconnect = e => { e.ports[0].postMessage(++conns); }');
worker.port.onmessage = e => {
  parent.postMessage(e.data, '*');
}

</script>
</body>
</html>
