when/sequence.js

/** @license MIT License (c) copyright 2011-2013 original author or authors */

/**
 * sequence.js
 *
 * Run a set of task functions in sequence.  All tasks will
 * receive the same args.
 *
 * @author Brian Cavalier
 * @author John Hann
 */

(function(define) {
define(function(require) {

	var when = require('./when');
	var all = when.Promise.all;
	var slice = Array.prototype.slice;

	/**
	 * Run array of tasks in sequence with no overlap
	 * @param tasks {Array|Promise} array or promiseForArray of task functions
	 * @param [args] {*} arguments to be passed to all tasks
	 * @return {Promise} promise for an array containing
	 * the result of each task in the array position corresponding
	 * to position of the task in the tasks array
	 */
	return function sequence(tasks /*, args... */) {
		var results = [];

		return all(slice.call(arguments, 1)).then(function(args) {
			return when.reduce(tasks, function(results, task) {
				return when(task.apply(void 0, args), addResult);
			}, results);
		});

		function addResult(result) {
			results.push(result);
			return results;
		}
	};

});
})(typeof define === 'function' && define.amd ? define : function (factory) { module.exports = factory(require); });