Hi Nathan,

Please refer to this link below for client side validation using the
CustomValidator control.

http://quickstarts.asp.net/QuickStartv20/aspnet/doc/validation/default.aspx

The CustomValidator server control calls a user-defined function to perform
validations that the standard validators can't handle. The custom function
can execute on the server or in client-side script, such as JScript or
VBScript. For client-side custom validation, the name of the custom function
must be identified in the ClientValidationFunction property. The custom
function must have the form function myvalidator(source, arguments). Note
that source is the client-side CustomValidator object, and arguments is an
object with two properties, Value and IsValid. The Value property is the
value to be validated and the IsValid property is a Boolean used to set the
return result of the validation.

Regards,
Manish

www.ComponentOne.com

the basevalidator has no builtin support for calling clientfunctions, you
will need to write the hookup code yourself. client validation is pretty
simple. validators are rendered as a span. then javascript code is rendered
to create a javascript variable that references the span. then expando
properties are added to this variable. your valiadation code would add
additional properties via RegisterExpandoAttribute.

there are 7 expando properties the base validator renders:

 enabled - bool used to enable/disable validation
 controltovalidate - the ClientId of the control to validate
 focusOnError - bool used to indicate set focus action
 errormessage - message to display if not valid
 display - display type
 isvalid - results of validation (set by the caller)
 validationGroup - the validation group

if you want a client function called, your code needs to add the expando
attribute:

 evaluationfunction - name of the client function to cal

the evaluationfunction is called with one arg, the validator instance. your
client code can then look at any expando attributes to decided what action to
take. this fuction should return true/false for valid/not valid

the CustomValidator will render the evaluationfunction based on the
ClientValidationFunction server property. it will call the client function
with two args

 clientFunction (val, args)

where val is the validaor instance, and args is an object with two properties

 args.Value - the value of the control to validate
 args.IsValid - always initialized to true
 
after the custom validator calls your client fucntion it returns
args.IsValid to its caller (the standard validation code), and does not  use
your functions return value.

one advantage of the custom validator (besides hooking the client function)
is it has generic code to determine the value of the control to validate. if
you use the base, you will need to write this code.

pretty simple actually.

-- bruce (sqlwork.com)