Are there any decent .NET MVC frameworks for building rich AJAX applications?

Question

I'd like to build an application(s) with rich ajax-based user interface. Key UI features would be:

• Realtime data saving (incomplete data that user typed in forms should be saved server side)
• Realtime validation (fields should be validated, sometimes validated using server side check, when lost focus)
• Handling URL navigation (with URL # fragment) and browser back button
• No page reloading

So in general I'd like the kind of UI like in google applications, wunderkit, asana. My application will have a lot of forms, lot of input fields and will have to deal with lot of data including file uploads. The previous version of the application use ASP.NET-MVC3 and ajax is used only in form of few dedicated modules. The requirement is to build it in .NET and I can't image using anything else than ASP.NET-MVC.

The question is: Is there any decent framework for building such appliactions with .NET MVC 4 or should I rather start building it myself?

UPDATE: I know there's lot of jQuery plugins for each of ajax UI features. I'm looking for some kind of base for rich ajax applications where these plugins are already chosen. Although I'm starting to realize that maybe creating this base by myself is a better idea.

Answer 1

Sometimes it's not "invent the wheel again" out there exist so many javascripts libraries to help you. the level of abstraction you're looking for, you don't find something, at least good.

I always do custom libraries who adapts to the design and keeps the pattern who wants the client to re-use (DRY), remember that not everybody wants the same user interface flow

Answer 2

Just about everything you're asking about can be found in a jQuery plugin.