ws-playground/server/server.js

const WebSocket = require("ws");

const wss = new WebSocket.Server({port: 3001});

function users() {
    results = [];

    wss.clients.forEach(function(client) {
        // goes inside "data"
        results.push({
            "user": client.user,
            "status": client.readyState,
        });
    });

    return results;
}

function send(payload) {

    let message = JSON.stringify({
        "to": payload.to,
        "from": payload.from,
        "type": payload.type,
        "subject": payload.subject || "",
        "body": payload.body,
        "data": payload.data || {},
        "date": Date.now()
    });

    // work as 'array', not 'set'
    let clients = Array.from(wss.clients);

    if(!clients.length) return false;

    let to = clients.find(function(client) {
        console.log('user', client.user);

        if(client.user === payload.to) {
            client.send(message);

            return true;
        }
    });

    // carbon copy
    if(to && payload.type === 'message') {
        let from = clients.find(function(client) {

            if(client.user === payload.from) {
                client.send(message);

                return true;
            }
        });
    }

    console.log('sent', !!to);

    return !!to;
}

function message(payload) {
    return {
        "type": payload.type || "message",
        "to": payload.to,
        "from": payload.from || "",
        "subject": payload.subject || "",
        "body": payload.body || "",
        "data": payload.data || {},
        "date": Date.now()
    }
}


function broadcast(data) {

    wss.clients.forEach(function(client) {
        client.send(JSON.stringify(data));
    });
}

wss.on('connection', function(client) {

    console.log('client connected');

    client.on('message', function(payload) {
        console.log('RECIEVED:', payload);

        try {
            payload = JSON.parse(payload);

            switch(payload.type) {
                case 'register':
                    // attach user id
                    client.user = payload.user;

                    broadcast({type: "clients", data: users(), "date": Date.now()});

                    console.log('CLIENT REGISTERED', client.user);

                    break;
                case 'clients':
                    // update clients on page
                    break;
                case 'message':
                    console.log('message', payload);
                    return send(payload);
                case 'broadcast':
                    payload.date = Date.now();

                    broadcast(payload);
                case 'notification':
                    return send(payload);
            }

        } catch(err) {
            console.log(err);
        }
    });

    client.on('close', function(e) {
        console.log('client left', e);

        broadcast({type: "clients", data: users(), "date": Date.now()});
    });

    client.on('error', function(e) {
        console.log('client error', e);

    });
});

wss.on('error', function(err) {
    console.log('ERROR', err);
});

wss.on('close', function(e) {
    console.log('close', e);
});

process.on('SIGINT', function () {
    console.log("Caught interrupt signal");
    broadcast({type: "offline", "date": Date.now()});

    process.exit();
});


function opcodes() {
    /*
        0	Continuation Frame	[RFC6455]
        1	Text Frame	[RFC6455]
        2	Binary Frame	[RFC6455]
        3-7	Unassigned
        8	Connection Close Frame	[RFC6455]
        9	Ping Frame	[RFC6455]
        10	Pong Frame	[RFC6455]
        11-15	Unassigned

    */
}

function close(code) {
    switch(code) {
        case 1000:
            return 'Normal Closure';
        case 1001:
            return 'Going Away';
        case 1002:
            return 'Protocol Error';
        case 1003:
            return 'Unsupported Data';
        case 1004:
            return 'Reserved';
        case 1005:
            return 'No Status Rcvd';
        case 1006:
            return 'Abnormal Closure';
        case 1007:
            return 'Invalid frame payload data';
        case 1008:
            return 'Policy Violation';
        case 1009:
            return 'Message Too Big';
        case 1010:
            return 'Mandatory Ext.';
        case 1011:
            return 'Internal Error';
        case 1012:
            return 'Service Restart';
        case 1013:
            return 'Try Again Later';
        case 1014:
            return 'Invalid Proxy/Gateway Response';
        case 1015:
            return 'TLS Handshake';
        default:
            return 'Reserved for Private Use';
    }
}


class SocketServer extends WebSocket.Server {
    constructor(opts) {
        super(opts);


    }

    users() {
        results = [];

        this.clients.forEach(function(client) {
            // goes inside "data"
            results.push({
                "user": client.user,
                "status": client.readyState,
            });
        });

        return results;
    }
}