demo-server.js

var fs = require('fs');
var express = require('express');
var app = express();
var peers = {};

var server = require('http').createServer(cb);
var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({
  server: server
});

var port = 5552;
server.listen(port);
console.log('Listening on port', port);

app.use(function(req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  next();
});

wss.on('connection', function connection(ws) {
  var id;
  ws.on('message', function incoming (message) {
    var original = message;
    try {
      message = JSON.parse(message);
    } catch (e) {
      console.error('Invalid JSON message');
    }
    switch (message.type) {
      case 'init':
        console.log('Init Message from', message.source);
        id = message.source;
        peers[message.source] = ws;
        ws.send(JSON.stringify({
          type: 'init',
          target: id
        }));
        break;
      default:
        console.log('Message from', message.source, 'to', message.target);

        if (peers[message.target]) {
          peers[message.target].send(original);
        } else {
          ws.send(JSON.stringify({
            type: 'error',
            target: id,
            error: 'There\'s no connection established with ' + message.target
          }));
        }
    }
  });
  ws.on('close', function close() {
    console.log('delete peer with id: ', id);
    delete peers[id];
  });
});