I have a custom validation function in JavaScript in a user control on a .Net 2.0 web site which checks to see that the fee paid is not in excess of the fee amount due.

I've placed the validator code in the ascx file, and I have also tried using Page.ClientScript.RegisterClientScriptBlock() and in both cases the validation fires, but cannot find the JavaScript function.

The output in Firefox's error console is "feeAmountCheck is not defined". Here is the function (this was taken directly from firefox->view source)

<script type="text/javascript">
function feeAmountCheck(source, arguments)
var amountDue = document.getElementById('ctl00_footerContentHolder_Fees1_FeeDue');
var amountPaid = document.getElementById('ctl00_footerContentHolder_Fees1_FeePaid');
if (amountDue.value > 0 && amountDue >= amountPaid)
arguments.IsValid = true;
arguments.IsValid = false;
return arguments;


Any ideas as to why the function isn't being found? How can I remedy this without having to add the function to my master page or consuming page?

Thanks in advance.

+1  A: 

If you're using .Net 2.0 and Ajax - you should use:


It will work better in Ajax environments then the old Page.ClientScript version.

+3  A: 

Try changing the argument names to "sender" and "args". And, after you have it working, switch the call over to ScriptManager.RegisterClientScriptBlock, regardless of AJAX use.

Greg Hurlman

@bcaff86 - Thanks for the ScriptManager tip. I am using Ajax and the user control (an validation code) are inside of an update panel. Unfortunately, that didn't expose the function.

@modesty - What I pasted in is the generated output from Firefox. I am using .ClientID in the actual code.

Rob Allen

While I would still like an answer to why my JS wasn't being recognized, the solution I found in the meantime (and should have done in the first place) is to use an Asp:CompareValidator instead of an Asp:CustomValidator.

Rob Allen

Also you could use:

var amountDue = document.getElementById('<%=YourControlName.ClientID%>');

That will automatically resolve the client id for the element without you having to figure out that it's called 'ctl00_footerContentHolder_Fees1_FeeDue'.