Matt O'Kane - ASP.NET Client-side validation Controls that work in Firefox as well as Internet Explorer: "ASP.NET Client-side validation Controls that work in Firefox as well as Internet Explorer
Here, you can download controls that work the same as ASP.NET standard validation controls with two important differences. Firstly, the controls will work in Firefox 1.0 and later, as well as IE. Secondly, they are fully HTML DOM compliant.
This work is a minor improvement on the fantastic work by Paul Glavich.
For all intensive purposes, these controls work exactly the same as the regular validation controls (that is CompareValidator, CustomValidator, ValidationSummary, RangeValidator, RegularExpressionValidator, and RequiredValidator) except their names are slighlty different. But the properties and methods are a one-to-one match.
To run these, you need to refer to the compiled DLL (in the Release directory). This will add the controls.
Also the source code (in c#) is included in case you want to compile or modify the library yourself."