title: jquery ui sortable - sort by attribute value
body: <p>If I'm running jquery ui and using sortable in a ul element:</p>
  
  <pre><code>$("#example").sortable({
      update: function () {
          //do something
      }
  });
  
  &lt;ul id="example"&gt;
  &lt;li data-ex="1.1"&gt;&lt;/li&gt;
  &lt;li data-ex="0.1"&gt;&lt;/li&gt;
  &lt;li data-ex="1.4"&gt;&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>Is there a way to trigger an event that sorts my elements by the data attribute on the fly? Essentially I'd like a button that sorts the li elements by the data attribute also also triggers the update in sortable().</p>