JavaScript code not working

var counterModule = (function() {
	var counter = 0;
		
	return {
		incrementCounter: function () {
			 counter++;
       alert(counter++);
		},
		resetCounter: function () {
			counter = 0;
			alert("counter value prior to reset: " + counter);
		}
	};
}

counterModule.incrementCounter();
counterModule.incrementCounter();
counterModule.incrementCounter();
counterModule.resetCounter();