var MODULE = function () {
	var privateVar = 4

	var privateMethod = function(arg) {
		//body here.
	};

	return {
		publicMethod : function(arg) { //so when you instantiate this module, you get a single method back. Could return a complex object via json instead here though that relies on the private state.
			privateMethod(arg);
		},
	};
}();

http://www.infoq.com/presentations/JavaScript-Functions

Javascript encapsualtion via the module pattern

JavaScript