device.js

var webWs = new WebSocket("ws://192.168.147.157:8443/ws");

webWs.onopen = () => {
    webWs.send(JSON.stringify({
        cmd:"register",
        clientid:"web",
        roomid:"adminroom"  
    })
    );
};

webWs.onmessage = evt => {
    console.log("web client received:", evt.data);
    var data = JSON.parse(evt.data);
    if (data.msg != "") {
        var msg = JSON.parse(data.msg);
        switch (msg.type){
        case 'req':
            webWs.send(JSON.stringify({
                cmd:'invite',
                clientid: 'web',
                roomid: 'adminroom',
                msg: JSON.stringify({
                    type:'accept',
                    groupid: msg.groupid
                })
            }));            
        }
    }
};

var deviceWs = new WebSocket("ws://192.168.147.157:8443/ws");
deviceWs.onmessage = function(evt) {
    console.info("device received: ", evt.data)
};
deviceWs.onopen = () => {
    /*
    window.onbeforeunload = () => {
        deviceWs.send(JSON.stringify({
            cmd:'send',
            msg: JSON.stringify({type: 'bye'})
            })
         );
    };
    */   
    deviceWs.send(JSON.stringify({
        cmd: 'register',
        roomid: 'adminroom',
        clientid: 'xxxxxxxxxxxx'
        })
    );
    setTimeout(function() {
        if (deviceWs.readyState == 1) {
            deviceWs.send(JSON.stringify({
                msg: JSON.stringify({
                    "type": "req",
                    "groupid": "123"
                }),
                cmd: "invite",
                roomid: "adminroom",
                clientid: "xxxxxxxxxxxx"
            }));
        }
    }, 1000);   
};