Node.jsでの処理同期化いろいろ

sync.js

function each(arr, iterator, onEnd) {
	var endIdx = arr.length - 1;
	arr.forEach(function(i, idx) {
		iterator.apply(this, [i, idx,
		function() {
			if (idx === endIdx) {
				if ( typeof onEnd === 'function') {
					setImmediate(onEnd);
				}
			}
		}]);
	});
}

function serial(arr, iterator, onEnd) {
	var endIdx = arr.length - 1;
	if (endIdx < 0) {
		onEnd();
		return;
	}

	setImmediate(loop, 0);

	function loop(idx) {
		setImmediate(iterator, arr[idx], idx, function() {
			if (idx === endIdx) {
				if ( typeof onEnd === 'function') {
					setImmediate(onEnd);
				}
			} else {
				setImmediate(loop, idx + 1);
			}
		});
	}

}

function synchronized(funcs, onEnd) {
	serial(funcs, function(func, idx, next) {
		setImmediate(func, idx, next);
	}, onEnd);
}