<!DOCTYPE html>
<html>
    <head>
        <style>
            iframe { border: 1px solid black; }
        </style>
        <script>
            function log(msg)
            {
                document.getElementById("console").innerHTML += msg + "<br>";
            }

            async function test(event)
            {
                await navigator.mediaDevices.getUserMedia({video: true, audio: true });
                let devices = await navigator.mediaDevices.enumerateDevices();
                let result = {
                    origin: document.origin, 
                    devices: devices.map(device => { return {deviceId: device.deviceId, kind: device.kind} }),
                };

                parent.postMessage(result, "*");
                
                let parentPage = document.referrer.split('/').pop();
                if (parentPage != "enumerate-devices-source-id.html")
                    return;

                let iframe = document.createElement('iframe');
                iframe.src = location.href;
                document.body.appendChild(iframe);
            }

            function handler(event) 
            {
                let result = {
                    origin: `${event.data.origin}`, 
                    devices: event.data.devices
                };

                parent.postMessage(result, "*");
            }

            addEventListener("message", handler, false);

        </script> 
    </head>
    <body onload="test()">
        <pre id="console"></pre>
    </body>
</html>