async.mini.js

var async = {
	parallel: function(funcs, complete) {
		console.log("parallel")
		var counter = 0
		var callback = function(argument) {
			counter = counter + 1
			if (counter == funcs.length) {
				setTimeout(complete, 0);
			}
		}

		funcs.map(function(func) {
			func(callback)
		})
	},
	series: function(funcs, complete) {
		console.log("series")
		var counter = 0
		var callback = function(argument) {
			counter = Number(counter) + Number(1)
				// console.log("couneting", counter)

			if (counter >= funcs.length) {
				setTimeout(complete, 0);
			} else {
				funcs[counter](callback)
			}
		}

		funcs[0](callback)
	},
	waterfall: function(funcs, complete) {
		console.log("series")
		var counter = 0
		var callback = function(argument) {
			counter = Number(counter) + Number(1)

			if (counter >= funcs.length) {
				setTimeout(complete, 0);
			} else {
				var result = funcs[counter](argument,callback)
			}
		}

		funcs[0](null,callback)
	},
	waterpool: function(funcs, complete) {
		console.log(funcs)
		var counter = 0
		var returnValues = {}
		var caller = function(returnValue){
			counter = counter + 1
			console.log(counter)
			returnValues[counter] = returnValue
			if(counter == funcs.length){
				complete(returnValues)
			}
		}

		funcs.map(function(func){
			func(caller)
		})
	}
}


// call all together and when all comeplete, notify
async.parallel(
	[
		function(callback) {
			console.log("1")
			callback()
		},
		function(callback) {
			setTimeout(function() {
				console.log("2")
				callback()
			}, 3000);
		},
		function(callback) {
			console.log("3")
			callback()
		}
	],
	function(done) {
		console.log("completed calling them parallel")
	})

// call all one by one in order and when they all finish, notify
async.series(
	[
		function(callback) {
			console.log("1")
			callback()
		},
		function(callback) {
			setTimeout(function() {
				console.log("2")
				callback()
			}, 3000);
		},
		function(callback) {
			console.log("3")
			callback()
		}
	],
	function(done) {
		console.log("completed calling them in series")
	})
	
// call all of them in parallel and collect the return values, then provide that result on completing
async.waterpool(
	[
		function(callback) {
			console.log("1")
			callback("returned from 1")
		},
		function(callback) {
			setTimeout(function() {
				console.log("2")
				callback("returned from 2")
			}, 3000);
		},
		function(callback) {
			console.log("3")
			callback("returned from 3")
		}
	],
	function(results) {
		console.log(results)
		console.log("completed calling them waterpool")
	})

// call all the functions and provide the result of the previous function to the next one. till they are over
async.waterfall(
	[
		function(result,callback) {
			console.log(result,"1")
			callback("returned from 1")
		},
		function(result,callback) {
			setTimeout(function() {
				console.log(result,"2")
				callback("returned from 2")
			}, 3000);
		},
		function(result,callback) {
			console.log(result,"3")
			callback("returned from 3")
		}
	],
	function(done) {
		console.log("completed calling them waterlfall")
	})