resource-timing/resources/iframe-post-message.html - external/github.com/web-platform-tests/wpt - Git at Google

 <!doctype html>
 <html>
   <script>
     window.addEventListener('message', e => {
       const port = e.ports?.[0];
       port.postMessage("hello from iframe");
     });
   </script>
 </html>
	<!doctype html>
	<html>
	<script>
	window.addEventListener('message', e => {
	const port = e.ports?.[0];
	port.postMessage("hello from iframe");
	});
	</script>
	</html>