jQuery - get the index of a element with a certain class
<p>I have a list like this one:</p>

<pre><code>&lt;li&gt; .... &lt;/li&gt;
&lt;li&gt; .... &lt;/li&gt;
&lt;li&gt; .... &lt;/li&gt;
&lt;li class="active"&gt; .... &lt;/li&gt;
&lt;li&gt; .... &lt;/li&gt;
</code></pre>

<p>I want to find out the index (number in the list) of the item with the "active" class element.
in this case the index would be 4 (or 3 if we're starting from 0)
How can I do that?</p>
