How do jquery library implement the $("") in jquery-1.x.x.js source code?
<p>Recently I begin to study the jquery, I feel confused how jquery library implement the <strong>$</strong>, I walked through the jquery source code and still cannot understand it.</p>

<p>Why  is <strong>$( "#xid" )</strong> equivalent to <strong>getElementById("xid")</strong>?</p>

<p>Could you please explain <strong><em>$</em></strong> for me according to the <strong>source code of jquery</strong>?</p>

<p>thanks.</p>
