title: Find "ul" elements that does not have "li" elements using jquery
body: <p>So lets say i have this html code</p>
  
  <pre><code>&lt;ul id="mainUL"&gt;
  &lt;li&gt;
     &lt;ul&gt;&lt;/ul&gt;
  &lt;/li&gt;
  &lt;li&gt;
     &lt;ul&gt;
      &lt;li&gt;One&lt;/li&gt;
      &lt;li&gt;Two&lt;/li&gt;
     &lt;/ul&gt;
  &lt;/li&gt;
  &lt;li&gt;
     &lt;ul&gt;
     &lt;/ul&gt;
  &lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>Is there a way to find those ul that does not contain any li elements? My code is quite dynamic so it is hard for me to insert a class or id to append those ul. Do i use jquery <code>.find()</code> or jquery <code>.children()</code>? And how do I apply these <code>$('ul')</code>?</p>