@nathanfaucett/parallel/src/fromArray.js

parallel for the browser and node.js

var once = require("@nathanfaucett/once"),
	asyncDone = require("@nathanfaucett/async_done"),
	arrayForEach = require("@nathanfaucett/array-for_each"),
	throwIfNotFunction = require("./throwIfNotFunction");

module.exports = fromArray;

function fromArray(tasks) {
	var taskLength = tasks.length;

	arrayForEach(tasks, throwIfNotFunction);

	return function runArray(callback) {
		var onceCallback = once(callback),
			results = new Array(taskLength),
			count = taskLength;

		function onResult(error, index, result) {
			results[index] = result;

			if (error) {
				onceCallback(error, results);
			} else if (--count === 0) {
				onceCallback(undefined, results);
			}
		}

		arrayForEach(tasks, function each(task, index) {
			asyncDone(task, function onAsyncDone(error, result) {
				onResult(error, index, result);
			});
		});
	};
}