title: How to get element order number
body: <p>how can i get order number of some element by javascript/jquery?</p>
  
  <pre><code>&lt;ul&gt;
   &lt;li&gt;Anton&lt;/li&gt;
   &lt;li class="abc"&gt;Victor&lt;/li&gt;
   &lt;li class="abc"&gt;Simon&lt;/li&gt;
   &lt;li&gt;Adam&lt;/li&gt;
   &lt;li&gt;Peter&lt;/li&gt;
   &lt;li class="abc"&gt;Tom&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>There is 3xli with abc class. Now I need to get order(sequence) number of Simon li.</p>
  
  <p>Thanks in advance</p>