title: What does webform_DoPostBackWithOptions() do?
body: <p>I have a button declared like this:</p>
  
  <pre><code>&lt;asp:Button id=Send runat="server" EnableViewState="False" 
  ToolTip="Email me this report" CssClass="Button" Text="Email me this report"&gt;
  &lt;/asp:Button&gt;
  </code></pre>
  
  <p>But if I do Inspect Element in browser, it shows like this:</p>
  
  <pre><code>&lt;input type="submit" class="Button" title="Email me this report" 
  id="ctl03_Toolbar_Send" onclick="javascript:WebForm_DoPostBackWithOptions(new 
  WebForm_PostBackOptions("ctl03$Toolbar$Send","", true, "", "";, false, false))" 
  value="Email me this report" name="ctl03$Toolbar$Send"&gt;
  </code></pre>
  
  <p>I wonder where the onclick event comes from? What does it do?</p>
  
  <p>Thanks for your help in advance.</p>