<!DOCTYPE html>
<html>
<body>
    <iframe id="myFrame"></iframe>
    <script>
const html = "<body" + ">PASS<script" + ">parent.postMessage('loaded', '*')</"+ "script></" + "body>";
var blob = new Blob([html], {type: 'text/html'});
var url = URL.createObjectURL(blob);
myFrame.src = url;
window.onmessage = (event) => {
    parent.postMessage(event.data, '*');
};
    </script>
</body>
</html>