teste.html

<html>
	<head>
	</head>
	<body>
		<h1 id="value">0</h1>
		<button id="increment">Incrementar</button>
		<button id="decrement">Decrementar</button>
	</body>
	<script type="text/javascript">

		var count = function (){
			var value = 0;

			var update = function () {
				document.getElementById('value').innerHTML = value;
			}

			var increment = function () {
				++value;
				update();
			}

			var decrement = function () {
				--value;
				update();
			}

			var init = function () {
				document.getElementById('increment').onclick = increment;
				document.getElementById('decrement').onclick = decrement;
			}

			return { init: init }

		};

		count().init();

	</script>
</html>