title: callback for facebook share button using addthis
body: <p>I am using addThis for facebook share option.</p>
  
  <pre><code>&lt;a class="addthis_button_preferred_1"&gt;&lt;/a&gt;
  &lt;a class="addthis_button_preferred_2"&gt;&lt;/a&gt;
  &lt;a class="addthis_button_preferred_3"&gt;&lt;/a&gt;
  </code></pre>
  
  <p>When the user completes facebook sharing I need to do functionalities.</p>
  
  <p>So guys please help me on how I can do a callback after successful sharing.</p>