title: Socket.io : "Cannot read property 'emit' of undefined"
body: <p>So I'm currently developping my website using socket.io.</p>
  
  <p>Today, while I was implementing the sockets, I got a nice little error <strong>"Cannot read property 'emit' of undefined"</strong>
  I can not find what's wrong in my code so I hope you guys can help me.</p>
  
  <p><strong>App.js:</strong></p>
  
  <pre><code>var socket  = require( 'socket.io' );
  var express = require('express');
  var app     = express();
  var server  = require('http').createServer(app);
  var io      = socket.listen( server );
  var port    = 9999;
  
  server.listen(port, function () {
    console.log('Listening at port %d', port);
  });
  
  io.sockets.on('connection', function (socket) {
      console.log('User connected');
  
      socket.on('create_socket', function(port){
      console.log(port);
  });
  </code></pre>
  
  <p><strong>Client Side:</strong></p>
  
  <pre><code>&lt;div&gt;
      &lt;p class="connected" hidden&gt;Connected port : 9999&lt;/p&gt;
      &lt;p class="connect_error" hidden&gt;&lt;strong&gt;Can not connect to socket on port 9999&lt;/strong&gt;&lt;/p&gt;
  &lt;/div&gt;
  
  &lt;script&gt;
      var socket = io.connect("http://localhost:9999");
  
      // If connection can not be established
      socket.on('connect_error', function(socket) {
          $('.connected').hide();
          $('.connect_error').show();
      });
  
      // Connection established
      socket.on('connect', function(socket) {
          $('.connect_error').hide();
          $('.connected').show();
         // socket.on('create_socket', null, &lt;?= $port; ?&gt; );
         socket.emit('create_socket', '&lt;?= $port; ?&gt;');
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>Btw, all the socket.io/jquery/... includes are done correctly even if they doesn't appear on the code</p>
  
  <p>Thanks in advance</p>