title: Ruby convert DateTime to milliseconds
body: <p>How do I convert this JavaScript function to Ruby?</p>
  
  <pre><code>new Date().getTime()
  </code></pre>
  
  <p>That returns:</p>
  
  <blockquote>
    <p>1384520363488</p>
  </blockquote>
  
  <p>I’m having trouble getting the same answer using Ruby DateTime, TimeAt, etc.</p>