title: Why does new Date(undefined) create an invalid date, but new Date(null) does not?
body: <p>I noticed something odd today with Javascript:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>console.log(new Date(null)); // 1970-01-01T00:00:00.000Z
  console.log(new Date(undefined)); // Invalid Date</code></pre>
  </div>
  </div>
  </p>
  
  <p>Why is this the case? I know null and undefined are not the same, but in this context I would expect the same result.</p>