Why is jQuery.getJSON structured the way it is?

Question

Why is the getJSON function structured this way?

 $.getJSON( url [, data ] [, success ] )

Instead of just returning an object, ie:

 var myjson = $.getJSON( url [, data ])

Answer 1

Because it returns a jqXHR object that contains responseText and responseXML properties, as well as a getResponseHeader() method. When the transport mechanism is something other than XMLHttpRequest (for example, a script tag for a JSONP request) the jqXHR object simulates native XHR functionality where possible. Basically, how would you know if the request was successful?