Untitled

<html>
  <head>
    <script type="text/javascript" src="http://code.jquery.com/jquery-2.1.4.min.js"></script>
    <script type="text/javascript">
      jQuery(document).ready(function(){

        $('#block').bind("DOMSubtreeModified",function(){
          alert('changed');
        });

      });

      // Emulate Taboola loading.
      setTimeout(function(){
        $('#block').html('<h1>Taboola!!!</h1>');
      }, 3000);
    </script>
  </head>
  <body>
    <div id="block">
      Loading....
    </div>
  </body>
</html>