Can only give you hints, lazy to write the solutions

if for Javascript, u can use JSON.
or u can use WebServices (asmx will be enuf)

or more tricky way:
1) add updatepanel to ur page
2) add a hidden button (btnCheckEmail) which to postback to server for CheckEmailExists() function
3) bind a jscript to ur txtEmail to call __doPostBack('btnCheckEmail_ClientId','')
4) bingo~

happy coding

This post has been edited by eueu: Aug 27 2011, 11:37 AM

Try to use document.getElementById instead of $get("")

If still cant, read this article.
http://brian.dobberteen.com/code/jquery_aj...stom_validator/