Simple utility for parallel execution of asynchronous tasks in JavaScript

collector.js

function collector() {
  var c = {}, errors  = {}, results = {}, pending = 1, callback = null

	c.bind = function(name) {
		pending++
		return function(err, result) {
			if (err)  errors[name] = err
			else     results[name] = result
			fireIfFinished()
		}
	}

	c.collect = function(_callback) {
		callback = _callback
		fireIfFinished()
	}

	function fireIfFinished() {
		pending--
		if (pending === 0) {
			callback(errors, results)
		}
	}

	return c
}


var c  = collector()
var fs = require('fs')

fs.stat(__dirname + "/collector.js", c.bind('foo')) // this file should exist. It is actually this file
fs.stat(__dirname + "/bar.js", c.bind('bar')) // this file should not exist

c.collect(function(errors, results) {
	console.log('foo', results.foo)
	console.log('bar', errors.bar)
})