Do something on success response for remote validation in mvc

I am using remote validation to check the availability of username during registration for my asp.net mvc 3 applicaion (C#).

I am using MVC remote Attribute validation as:

[Remote("IsUserNameAvailable", "User")]
public string UserName { get; set; }

When I return this:

return Json(true, JsonRequestBehavior.AllowGet);

Then I want to perform something like set the hidden field value, which is return from action or show green icon image. And i want to also return ID with true.

How to achieve this things ?

In short, I want to do something on success.