Are you extjs programmer? Are you jquery programmer? Don’t worry, you can run both of them on same page. I will give you some tips to avoid a crashes. Below is the part of code:

<html>
  <head>

    <link href="css/extjs/resources/css/ext-all.css" rel="stylesheet" type="text/css" />
//include your jquery library
    <script type="text/javascript" src="js/jquery.js"></script>
//include adapter for using extjs and jquery on same page
    <script type="text/javascript" src="js/extjs/adapters/ext-jquery-adapter.js"></script>
    <script type="text/javascript" src="js/extjs/ext-all.js"></script>

    <script type="text/javascript">
      $().ready(function(){
        $('#askme').click(function(){
          Ext.Messagebox.confirm('Pertanyaan', 'Apakah anda suka framework.web.id?');
        })
      })
    </script>

  </head>
  <body>
    <button id="askme">Ask Me!</button>
  </body>
</html>

The important code is below :

<script type="text/javascript" src="js/jquery.js"></script>
<script type="text/javascript" src="js/extjs/adapters/ext-jquery-adapter.js"></script>
<script type="text/javascript" src="js/extjs/ext-all.js"></script>

They should be sequentially. Tyr it. Done !

You can run extjs with other javascript framework such as prototype, jquery, yui. See include-order.txt file at extjs root directory and try it same as my way above.