title: Why does NaN != undefined?
body: <p>According to the <a href="https://developer.mozilla.org/en/docs/JavaScript/Guide/Values,_variables,_and_literals" rel="noreferrer">Mozilla docs</a>:</p>
  
  <blockquote>
    <p>The undefined value converts to NaN when used in numeric context.</p>
  </blockquote>
  
  <p>So why do both of the following equate to true?:</p>
  
  <pre><code>NaN != undefined
  NaN !== undefined
  </code></pre>
  
  <p>I could understand <code>Nan !== undefined</code> as the variable type would be different...</p>