typeof a === 'undefined'
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/4725603/variable-undefined-vs-typeof-variable-undefined">variable === undefined vs. typeof variable === “undefined”</a>  </p>
</blockquote>



<p>Assuming that <code>undefined</code> has not been tampered with, are the following equivalent?</p>

<pre><code>typeof a === 'undefined'
</code></pre>

<p>and </p>

<pre><code>a === undefined
</code></pre>

<p>?</p>

<p>[The reason I ask is because the author of <a href="https://raw.github.com/guillaumepotier/Parsley.js/master/parsley.js" rel="nofollow">Parsley.js</a> seems to love writing <code>'undefined' !== typeof someExpression</code>.]</p>
