server.js

const express = require('express');
const http = require('http');
const url = require('url');
const WebSocket = require('ws');

const app = express();

app.use(express.static('./'));

const server = http.createServer(app);
const wss = new WebSocket.Server({ server });

const viewers = [];
const players = [];

wss.on('connection', function connection(ws) {
  const location = url.parse(ws.upgradeReq.url, true);
  // You might use location.query.access_token to authenticate or share sessions
  // or ws.upgradeReq.headers.cookie (see http://stackoverflow.com/a/16395220/151312)

  ws.on('close', function close() {
    viewers.forEach(viewer => {
      if(viewer.ws === ws) {
        viewers.splice(viewers.indexOf(viewer), 1);
      } else if(viewer.players.indexOf(ws) !== -1) {
        sendMsg(viewer, ws, 'CLOSE');
        viewer.players.splice(viewer.players.indexOf(ws), 1);
      }
    });
    // if(viewers.indexOf(ws) !== -1) {
    //   viewers.splice(viewers.indexOf(viewers.filter(viewer => {
    //     return viewer.ws === ws
    //   })), 1);
    // }
    // if(players.indexOf(ws) !== -1) {
    //   sendMsg(ws, 'CLOSE');
    //   players.splice(players.indexOf(ws), 1);
    // }
  });

  ws.on('message', function incoming(message) {
    // console.log('received: %s', message);
    const parts = message.split(' ');

    if(parts[0] === 'INIT' && parts[1] === 'v') {
      // require('dns').lookup(require('os').hostname(), function (err, add, fam) {
        ws.send(viewers.length + '!CONF');
        viewers.push({
          ws: ws,
          players: []
        });
      // });

      return;
    }

    if(parts[0] === 'INIT' && parts[1] === 'c') {
      ws.send(viewers[parts[2]].players.length);
      viewers[parts[2]].players.push(ws);
    }

    viewers.forEach(viewer => {
      if(viewer.players.indexOf(ws) !== -1) {
        sendMsg(viewer, ws, message);
      }
    })
  });
});

function sendMsg(viewer, from, msg) {
  viewer.ws.send(viewer.players.indexOf(from) + '!' + msg);
}

server.listen(8080, function listening() {
  console.log('Listening on %d', server.address().port);
});