videocall.html

<html>
<script src='https://meet.jit.si/external_api.js'></script>
</head>
<body>

<button id="start" type="button">Start</button>
<div id="jitsi-container">
</div>

<script>
var button = document.querySelector('#start');
var container = document.querySelector('#jitsi-container');
var api = null;

button.addEventListener('click', () => {
    var possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var stringLength = 30;

    function pickRandom() {
    return possible[Math.floor(Math.random() * possible.length)];
    }

var randomString = Array.apply(null, Array(stringLength)).map(pickRandom).join('');

    var domain = "meet.jit.si";
    var options = {
        "roomName": randomString,
        "parentNode": container,
        "width": 600,
        "height": 600,
    };
    api = new JitsiMeetExternalAPI(domain, options);
});

</script>
</body>
</html>