Untitled

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Iframe cross-document messaging example (Iframe)</title>
</head>
<body>
<div>
    <p>Frame</p>
    <p id="messageBox">message</p>
</div>
</body>
<script type="application/javascript">
    (() => {

        let messageBox = document.getElementById("messageBox");

        window.onmessage = (e) => {

            if (e.data != null) {
                console.log(e.data);
                messageBox.innerHTML = e.data;
            }
        };

    })();
</script>

</html>