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