Variable assignment with || in value
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/2100758/javascript-or-variable-assignment-explanation">JavaScript OR (||) variable assignment explanation</a>  </p>
</blockquote>



<p>Can someone help explain what this line does, and how?</p>

<pre><code>var scrollTop = html.scrollTop || body &amp;&amp; body.scrollTop || 0;
</code></pre>
