Difference between jquery $('#my_id') and document.getElementById('my_id')?
<p>I tought $('#my_id1') was the same thing as document.getElementById('my_id1'). But it is parently not. What is the difference?</p>

<pre><code>(function( $ ) {
  $.fn.simple_hide_function = function() {
  var $t = this;
  $t.hide();
  };
})( jQuery );

$(window).load(function () {
var $div1 = $('#my_id1');
var $div2 = document.getElementById('my_id2');
$div1.simple_hide_function(); // this is working
$div2.simple_hide_function(); // but this is not working
});
</code></pre>

<p><strong>Adding example to make it more clear:</strong></p>

<pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8" /&gt;
&lt;title&gt;Untitled Document&lt;/title&gt;
&lt;/head&gt;

&lt;body&gt;

&lt;div id="my_id1" style="height:100px;background:#f00"&gt;div1&lt;/div&gt;
&lt;div id="my_id2" style="height:100px;background:#f00"&gt;div2&lt;/div&gt;



&lt;script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"&gt;&lt;/script&gt;
&lt;script&gt;

(function( $ ) {
  $.fn.simple_hide_function = function() {
  var $t = this;
  $t.hide();
  };
})( jQuery );

$(window).load(function () {
var $div1 = $('#my_id1');
var $div2 = document.getElementById('my_id2');
$div1.simple_hide_function();
$div2.simple_hide_function();
});

&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>
