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