sync.js

// TODO: abstract duplicate codes.
var sync = {
	pipe: function(callbacks, done) {
		var next = function(result) {
			var args = Array.prototype.slice.apply(arguments);
			var callback = callbacks.shift();
			if (callback) {
				args.push(next);
				callback.apply(null, args);
			} else {
				done && done.apply(null, args);
			}
		};
		next();
	},

	series: function(callbacks, done) {
		this.pipe(callbacks, done);
	},

	each: function(arr, iterator, done) {
		var items = [];
		var next = function() {
			var item = items.shift();
			if (item) {
				item.unshift(next);
				iterator.apply(null, item);
			} else {
				done && done();
			}
		};

		this.normalize(arr);

		next();
	},

	map: function(arr, iterator, done) {
		var items = [];
		var results = [];
		var next = function(result) {
			results.push(result);
			var item = items.shift();
			if (item) {
				item.unshift(next);
				iterator.apply(null, item);
			} else {
				done && done(results);
			}
		};

		var start = function() {
			var item = items.shift();
			if (item) {
				item.unshift(next);
				iterator.apply(null, item);
			} else {
				done && done(results);
			}
		};

		this.normalize(arr);

		start();
	},

	reduce: function(arr, iterator, initial, done) {
		var items = [];

		var next = function(result) {
			var item = items.shift();
			if (item) {
				item.unshift(result);
				item.unshift(next);
				iterator.apply(null, item);
			} else {
				done && done(result);
			}
		};

		this.normalize(arr);

		next(initial);
	},

	detect: function(arr, iterator, done) {
		var items = [];
		var currentItem;

		var next = function(result) {
			if (result) {
				done && done(arr[currentItem]);
			}
			var item = items.shift();
			if (item) {
				currentItem = item[1];
				item.unshift(next);
				iterator.apply(null, item);
			} else {
				done && done(undefined);
			}
		};

		items = this.normalize(arr);

		next(false);
	},

	while: function(test, body, done) {
		var next = function() {
			if (test()) {
				body.apply(null, [next]);
			} else {
				done && done(undefined);
			}
		}
		next();
	},

	normalize: function(src) {
		var items = [];

		if (src instanceof Array) {
			for (var i = 0; i < src.length; i++) {
				items.push([src[i], i]);
			}
		} else {
			for(var i in src) {
				if (src.hasOwnProperty(i)) {
					dest.push([src[i], i]);
				}
			}
		}

		return items;
	}
};
if (typeof window !== "undefined") { window.sync = sync; }
if (typeof exports !== "undefined") { exports.sync = sync; }