title: JavaScript checking for null vs. undefined and difference between == and ===
body: <ol>
  <li><p>How do I check a variable if it's <code>null</code> or <code>undefined</code> and what is the difference between the <code>null</code> and <code>undefined</code>?</p></li>
  <li><p>What is the difference between <code>==</code> and <code>===</code> (it's hard to search Google for "===" )?</p></li>
  </ol>