title: Error: bind EADDRINUSE null:80 in node.js
body: <p>when i execute the program with npm start, appears: </p>
  
  <pre><code>Error: bind EADDRINUSE null:80
      at Object.exports._errnoException (util.js:896:11)
      at exports._exceptionWithHostPort (util.js:919:20)
      at cb (net.js:1311:16)
      at rr (cluster.js:620:14)
      at Worker.&lt;anonymous&gt; (cluster.js:590:9)
      at process.&lt;anonymous&gt; (cluster.js:750:8)
      at emitTwo (events.js:111:20)
      at process.emit (events.js:191:7)
      at handleMessage (internal/child_process.js:718:10)
      at Pipe.channel.onread (internal/child_process.js:444:11)
  CLUSTER: Worker 177 disconnected from the cluster.
  CLUSTER: Worker 177 died with exit code 1 (null)
  CLUSTER: Worker 181 started
  events.js:160
        throw er; // Unhandled 'error' event
  </code></pre>
  
  <p>if change the port from 80 to 8080, the program executes, but don't conect to api.localhost:3000 </p>