title: ASP.net Button OnClick Validation
body: <p>I have an asp:button with an onclick property that posts back to the server.  I would like to do some validation on the contents of a textbox before I fire the postback.  I want to do the validation in javascript using some regex.</p>
  
  <p>I cannot use an asp:XXXXvalidator; I just can't due to what my web app does.</p>
  
  <p>Is there a way to call a javascript function from an asp:button that then calls the postback?</p>
  
  <p>I know I can use OnClientClick to call js from the asp:button, but once I call the JS how do I signal that I want to postback the button?</p>