<!DOCTYPE HTML> <html> <body> <script type="application/javascript"> function ok(what, msg) { window.parent.postMessage({type: what ? 'OK' : 'KO', msg: msg }, '*'); } window.addEventListener('message', receiveMessage, false); function receiveMessage(evt) { if (evt.data.type == 'PORT') { var port = evt.data.port; var counter = 0; port.onmessage = function(evt) { if (counter++ == 0) { ok(!(evt.data % 2), "The number " + evt.data + " has been received correctly by the iframe"); window.parent.postMessage({ type: 'PORT', port: port }, '*', [port]); } else { ok(false, "Wrong message!"); } } } else { ok(false, "Unknown message"); } } </script> </body> </html>