title: XMLHttpRequest is not defined in Cloud9 IDE?
body: <p>I defined a <code>XMLHttpRequest</code> in the Cloud9 IDE like this:</p>
  
  <pre><code>var xhr = new XMLHttpRequest();
  </code></pre>
  
  <p>But it prompted an error, saying <code>ReferenceError: XMLHttpRequest is not defined</code>.</p>
  
  <p>Is <code>XMLHttpRequest</code> defined in Cloud9 IDE?</p>
  
  <p>Thanks!</p>