<!-- jQuery: Validating an email. -->    $('#txtEmail').blur(function(e) {    var sEmail = $('#txtEmail').val();    if ($.trim(sEmail).length == 0) {    alert('Enter valid Email ID');    e.preventDefault();    }            var filter = /^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]    {2,4}|[0-9]{1,3})(\]?)$/;            if (filter.test(sEmail)) {    alert('Valid Email');    }     else {    alert('Email not valid');     e.preventDefault();    }    });    <!-- HTML: Validating an email-->    <asp:TextBox id="txtEmail" runat="server" />