title: About nodejs server.listen()
body: <p>I just started to learn about nodejs servers and websockets.
  Said I have this server written in javascript using socket.io and express.  </p>
  
  <pre><code>var app = require('express')(),
      server = require('http').Server(app),
      io = require('socket.io')(server),
      port = process.env.PORT || 8080;
  </code></pre>
  
  <p>Is there any difference between:</p>
  
  <pre><code>server.listen(port, function(){
      console.log("listening port " + port);
  });
  </code></pre>
  
  <p>and</p>
  
  <pre><code>server.listen(port);
  console.log("listening port " + port);
  </code></pre>
  
  <p>Apparently they work the same.</p>
  
  <p>So what actually server.listen() do?</p>