title: Why this javascript code gives error
body: <p>It gives the following error</p>
  
  <p>The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %>)</p>
  
  <p>My code is </p>
  
  <pre><code>  __doPostBack('&lt;%= btnExitChatRoom.ClientID %&gt;', '');
  </code></pre>