title: cancel postback from javascript on confirm popup
body: <p>Following this problem <a href="https://stackoverflow.com/questions/1245033/asp-net-onserverclick-event-handler-not-called-if-using-onclick">ASP.NET: OnServerClick event handler not called if using onclick</a></p>
  
  <p>I implemented a workaround:</p>
  
  <pre><code>&lt;button id="idBtnPrint" runat="server" type="submit" onserverclick="BtnPrint_Click" onclick="confirmImpression();"&gt;print&lt;/button&gt;
  </code></pre>
  
  <p>javascript function:</p>
  
  <pre><code>    function confirmImpression() {
  
          if (!confirm("sure ?"))
              arg.whatever;
  
      }
  </code></pre>
  
  <p>where confirmation is positive the postback is started when cancel the postback is not run (as I want) simply because an error generated js "arg is undefined" (normal because arg is not instanciate) script is locked and therefore no postback (as I want too).</p>
  
  <p>but how to do this properly. I would not see the error appear in the status bar in the browser.</p>
  
  <p>any suggestion is welcome!</p>
  
  <p>thank you</p>