Parent site

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    window.addEventListener('message', function (e) {

        console.log('message');

        e.source.postMessage('messageToIframe', '*');

    }, false);
</script>

<iframe src="http://localhost:63343/untitled/index.html" frameborder="0" width="800" height="600"></iframe>

<!--<script>-->
    <!--document.querySelector('iframe').addEventListener('load', function (e) {-->

        <!--e.target.contentWindow.postMessage('some', '*');-->

    <!--}, false);-->
<!--</script>-->
</body>
</html>