text: var express = require('express');
  var bodyParser = require('body-parser');
  var Pusher = require('pusher');
  
  var app = express();
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  
  // to serve our JavaScript, CSS and index.html
  app.use(express.static('./'));
  
  var pusher = new Pusher({
    appId: '689201',
    key: '406ed04dbe9492a5eb23',
    secret: '96599cf8f20bc09cc412'
  });
  
  app.post('/pusher/auth', (req, res) => {
    var socketId = req.body.socket_id;
    var channel = req.body.channel_name;
    var auth = pusher.authenticate(socketId, channel);
    res.send(auth);
  });
  
  var port = process.env.PORT || 5000;
  app.listen(port, () => console.log('Listening at http://localhost:5000'));
  