title: create child div in a parent div using jquery
body: <p>I have the following div structure</p>
  
  <pre><code>&lt;div id="main_div"&gt;
      &lt;div id="lastChildDiv"&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>now I want to create or append a new <code>div</code> above the div id of <code>lastChildDiv</code>. Then how to do it?</p>