Question

I’m trying to turn on/off various RequiredFieldValidator controls when checkboxes are checked/unchecked, based on this question. But rather than having a separate js function for each checkbox I want to pass in the ClientID of the input to validate, something like this (only one INPUT here but you can see once it’s working I can add more INPUTs without more js):

<asp:TextBox ID="txtSubject" runat="server" />
<asp:CheckBox ID="chkSubjectRequired" runat="server" 
    OnClick="updateValidator('<%= rfvSubject.ClientID %>');" />
<asp:RequiredFieldValidator ID="rfvSubject" ControlToValidate="txtSubject" 
    ErrorMessage="You must enter a subject." runat="server" />

 <script>
 function updateValidator(inputId) {
      var enableValidator = !event.srcElement.checked;
      var theInput = document.getElementById(inputId);
      ValidatorEnable(theInput, enableValidator);
 }
 </script>

Currently that scriptlet txtSubject.ClientID isn’t evaluated, just output directly. I’m sure this is simple but I just don’t know the appropriate syntax.

Answer 1

How about adding it via the codebehind (or a script section):

checkSubjectRequired.Attributes.Add("onclick", "updateValidator(" + 
  txtSubject.ClientID + ")");

This explaination of ClientID may be helpful.