title: Prevent ASP.net __doPostback() from jQuery submit() within UpdatePanel
body: <p>I'm trying to stop postback on form submit if my custom jQuery validation returns false.</p>
  
  <p>Is there any way to prevent the __doPostback() function finishing from within the submit() function?</p>
  
  <p>I'd assumed:</p>
  
  <pre><code>$('#aspnetForm').submit(function () { return false; });
  </code></pre>
  
  <p>would do the trick, but apparently that's not the case: does anyone have a suggestion?</p>
  
  <p>The submit() function does block the postback (it won't postback if you pause at a breakpoint in firebug), but I can't seem to stop the event happening after the submit() function is complete!</p>
  
  <p>Cheers, Ed</p>
  
  <p>EDIT</p>
  
  <p>OK, I had a quick mess about and discovered that the fact that the button I'm using to cause the postback is tied to an updatepanel as an asyncpostbacktrigger seems to be the problem: If I remove it as a trigger (i.e. cause it to product a full postback), the is no problem preventing the postback with return false;</p>
  
  <p>Any ideas why the async postback would not be stoppable using return false?</p>