Question

What is the difference between

var createControl = function (attribute){ ...} 

and

$.fn.createControl = function (attribute) { .. }

in jQuery. What is the advantage of changing a function from $.fn.createControl to var createControl.

Answer 1

var foo = function (param) { ... }

Assigns a function to foo.

$.fn.foo = function (param) { ... } 

Extends the prototype of jQuery with foo. fn is just a shortcut to prototype and $ is a shortcut for jQuery. You could write the same thing as:

jQuery.prototype.foo = function (param) { ... }

The difference is that the former is just a variable within a certain scope, invisible outside of it. The later is a method extending the jQuery global object, thus making the variable accessible from anywhere since the jQuery object is attached to window, is global.