ASP.NET MVC Tip 3: Implementing remote client-side form validation

Client-side form validation has become a de-facto standard for modern web applications. However, there are some validation rules which cannot be checked completely on the client side, for example because the validation depends on information stored in the server database. For those rules you need to implement remote client-side form validation. This article describes how to implement this so that you don't have to write any custom javascript for new validation rules.