Question

I want to highlight text in control when validation occurs.

How can I achieve this?

<script language="javascript" type="text/javascript">
function changeColor(source, args) {
    var txt = document.getElementById('<%= txtAge.ClientID %>');
    if (args.Value.length >= 3) {
        txt.style.background = '#66CCFF';
        args.IsValid = false;
    }
    else {
        txt.style.background = 'none';
        args.IsValid = true;
    }
}
    
</script>

<asp:TextBox ID="txtAge" runat="server" ></asp:TextBox>
<asp:RequiredFieldValidator ID="rfldtxtAge" ErrorMessage="enter the value" ControlToValidate="txtAge"  runat="server" Display="Dynamic" SetFocusOnError="true" ForeColor="Red"></asp:RequiredFieldValidator>
   
<asp:CustomValidator ID="ctmtxtAge" runat="server" ClientValidationFunction="changeColor" ControlToValidate="txtAge" ErrorMessage="CustomValidator1" ></asp:CustomValidator>

I use this code for highlighting background of control, but I need to highlight the text of control.

Please help me.

Answer 1

Please use

 txt.select(); 

instead of

txt.style.background = '#66CCFF';

please let me know if this does not work.