Best-practive JavaScript class: "that" is public, "my" is private to the object.

JavaScript Class

var constructor = function (spec, my) {
	var that = {};
	var my = my || {};

	// This function is private.
	my.privateFunction = function() {
		return true;
	};

	// This function is public.
	that.publicFunction = function() {
		return true;
	};

	return that;
};