Hi nauna,
With RegularExpressionValidator it is not possible. For this you need to use CustomValidator and write your own logic.
Check this example. Now please take its reference and correct your code.
HTML
<asp:TextBox runat="server" ID="txtofferrate" />
<asp:CustomValidator ID="CustomValidator1" runat="server" ClientValidationFunction="Validate"
CssClass="validation" Display="Dynamic" ControlToValidate="txtofferrate" ErrorMessage="" ForeColor="Red" />
JavaScript
<script type="text/javascript">
function Validate(sender, args) {
var offerRate = document.getElementById(sender.controltovalidate).value;
var regex = /^[0-9]\d*(\.\d+)?$/;
if (regex.test(offerRate)) {
if (offerRate.split('.').length > 1) {
var value = offerRate.split('.')[0];
if (parseInt(value) == 0) {
if (value.length > 1) {
sender.innerHTML = "Valid Decimal Point Required."
args.IsValid = false;
}
}
}
else {
args.IsValid = true;
}
} else {
sender.innerHTML = "Valid Decimal Point Required."
args.IsValid = false;
}
}
</script>
Screenshot
