indexOf.call vs array.indexOf in jQuery's source
<p>I was browsing the source of <a href="https://github.com/jquery/jquery/blob/master/src/core.js#L680" rel="nofollow">jQuery</a> and bumped into this:</p>

<pre><code>return indexOf.call( array, elem );
</code></pre>

<p><em>- <a href="https://github.com/jquery/jquery/blob/master/src/core.js#L683" rel="nofollow">Line 683</a></em></p>

<p>I was wondering what was the logic behind that, and why not do:</p>

<pre><code>return array.indexOf(elem );
</code></pre>
