demo_module_1.js

var counter = (function () {

	var 
		_c = 0,
		increment = function () {
			return ++_c;
		},
		decrement = function() {
			return --_c;
		},
		reset = function() {
			return (_c = 0);
		};

	return {
		increment : increment,
		decrement : decrement,
		reset : reset
	};

})();

console.log("incrementing counter " + counter.increment());
console.log("incrementing counter " + counter.increment());
console.log("incrementing counter " + counter.increment());
console.log("incrementing counter " + counter.increment());

console.log("decrementing counter " + counter.decrement());
console.log("decrementing counter " + counter.decrement());

console.log("reseting counter " + counter.reset());