jquery - Serialize form data to JSON

I want to do some pre-server-validation of a form in a Backbone.js model. To do this I need to get the user input from a form into usable data.
I found three methods to do this:

1. var input = $("#inputId").val();


2. var input = $("form.login").serialize();


3. var input = $("form.login").serializeArray();

Unfortunately, none of the provide a good reabable and developable JSON object which I require. I already looked through several questions on Stack Overflow, but I found only some extra libraries.

Doesn't Underscore.js, the current jQuery or Backbone.js provide a helper method?

I can't imagine there is no request for such a function.

HTML

    username:
    
    password:
    
    

JavaScript

var formData = $("form.login").serializeObject();
console.log(formData);

Outputs

{
    "name": "dev.pus",
    "pass": "1234"
}

Backbone.js model

var user = new User(formData);
user.save();