webmessaging/postMessage_crosssite.sub.htm

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
async function addIframeAndReceiveMessage(path) {
  let url = new URL('resources/transfer-arraybuffer-to-parent.html', location);
  url.hostname = '{{hosts[alt][]}}';

  let frame = document.createElement('iframe');
  try {
    frame.src = url;
    document.body.appendChild(frame);
    return await new Promise((resolve, reject) => {
      window.addEventListener('message', e => resolve(e));
      window.addEventListener('messageerror', e => reject(new Error('received messageerror')));
    });
  } finally {
    frame.remove();
  }
}

promise_test(async () => {
  let messageEvent = await addIframeAndReceiveMessage('resources/transfer-arraybuffer-to-parent.html');
  assert_class_string(messageEvent.data, 'ArrayBuffer');
  assert_array_equals(new Uint8Array(messageEvent.data), [42, 222]);
}, "cross-site windows can send transferred ArrayBuffer");
</script>
</body>