| # run-parallel [![travis][travis-image]][travis-url] [![npm][npm-image]][npm-url] [![downloads][downloads-image]][downloads-url] [![javascript style guide][standard-image]][standard-url] |
| |
| [travis-image]: https://img.shields.io/travis/feross/run-parallel/master.svg |
| [travis-url]: https://travis-ci.org/feross/run-parallel |
| [npm-image]: https://img.shields.io/npm/v/run-parallel.svg |
| [npm-url]: https://npmjs.org/package/run-parallel |
| [downloads-image]: https://img.shields.io/npm/dm/run-parallel.svg |
| [downloads-url]: https://npmjs.org/package/run-parallel |
| [standard-image]: https://img.shields.io/badge/code_style-standard-brightgreen.svg |
| [standard-url]: https://standardjs.com |
| |
| ### Run an array of functions in parallel |
| |
|  [](https://saucelabs.com/u/run-parallel) |
| |
| ### install |
| |
| ``` |
| npm install run-parallel |
| ``` |
| |
| ### usage |
| |
| #### parallel(tasks, [callback]) |
| |
| Run the `tasks` array of functions in parallel, without waiting until the previous |
| function has completed. If any of the functions pass an error to its callback, the main |
| `callback` is immediately called with the value of the error. Once the `tasks` have |
| completed, the results are passed to the final `callback` as an array. |
| |
| It is also possible to use an object instead of an array. Each property will be run as a |
| function and the results will be passed to the final `callback` as an object instead of |
| an array. This can be a more readable way of handling the results. |
| |
| ##### arguments |
| |
| - `tasks` - An array or object containing functions to run. Each function is passed a |
| `callback(err, result)` which it must call on completion with an error `err` (which can |
| be `null`) and an optional `result` value. |
| - `callback(err, results)` - An optional callback to run once all the functions have |
| completed. This function gets a results array (or object) containing all the result |
| arguments passed to the task callbacks. |
| |
| ##### example |
| |
| ```js |
| var parallel = require('run-parallel') |
| |
| parallel([ |
| function (callback) { |
| setTimeout(function () { |
| callback(null, 'one') |
| }, 200) |
| }, |
| function (callback) { |
| setTimeout(function () { |
| callback(null, 'two') |
| }, 100) |
| } |
| ], |
| // optional callback |
| function (err, results) { |
| // the results array will equal ['one','two'] even though |
| // the second function had a shorter timeout. |
| }) |
| ``` |
| |
| This module is basically equavalent to |
| [`async.parallel`](https://github.com/caolan/async#paralleltasks-callback), but it's |
| handy to just have the one function you need instead of the kitchen sink. Modularity! |
| Especially handy if you're serving to the browser and need to reduce your javascript |
| bundle size. |
| |
| Works great in the browser with [browserify](http://browserify.org/)! |
| |
| ### see also |
| |
| - [run-auto](https://github.com/feross/run-auto) |
| - [run-parallel-limit](https://github.com/feross/run-parallel-limit) |
| - [run-series](https://github.com/feross/run-series) |
| - [run-waterfall](https://github.com/feross/run-waterfall) |
| |
| ### license |
| |
| MIT. Copyright (c) [Feross Aboukhadijeh](http://feross.org). |