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100 lines
2.9 KiB
100 lines
2.9 KiB
4 years ago
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# p-map [](https://travis-ci.org/sindresorhus/p-map)
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> Map over promises concurrently
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Useful when you need to run promise-returning & async functions multiple times with different inputs concurrently.
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## Install
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```
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$ npm install p-map
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```
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## Usage
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```js
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const pMap = require('p-map');
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const got = require('got');
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const sites = [
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getWebsiteFromUsername('https://sindresorhus'), //=> Promise
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'https://ava.li',
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'https://github.com'
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];
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(async () => {
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const mapper = async site => {
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const {requestUrl} = await got.head(site);
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return requestUrl;
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};
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const result = await pMap(sites, mapper, {concurrency: 2});
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console.log(result);
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//=> ['https://sindresorhus.com/', 'https://ava.li/', 'https://github.com/']
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})();
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```
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## API
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### pMap(input, mapper, options?)
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Returns a `Promise` that is fulfilled when all promises in `input` and ones returned from `mapper` are fulfilled, or rejects if any of the promises reject. The fulfilled value is an `Array` of the fulfilled values returned from `mapper` in `input` order.
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#### input
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Type: `Iterable<Promise | unknown>`
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Iterated over concurrently in the `mapper` function.
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#### mapper(element, index)
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Type: `Function`
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Expected to return a `Promise` or value.
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#### options
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Type: `object`
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##### concurrency
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Type: `number`<br>
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Default: `Infinity`<br>
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Minimum: `1`
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Number of concurrently pending promises returned by `mapper`.
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##### stopOnError
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Type: `boolean`<br>
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Default: `true`
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When set to `false`, instead of stopping when a promise rejects, it will wait for all the promises to settle and then reject with an [aggregated error](https://github.com/sindresorhus/aggregate-error) containing all the errors from the rejected promises.
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## Related
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- [p-all](https://github.com/sindresorhus/p-all) - Run promise-returning & async functions concurrently with optional limited concurrency
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- [p-filter](https://github.com/sindresorhus/p-filter) - Filter promises concurrently
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- [p-times](https://github.com/sindresorhus/p-times) - Run promise-returning & async functions a specific number of times concurrently
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- [p-props](https://github.com/sindresorhus/p-props) - Like `Promise.all()` but for `Map` and `Object`
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- [p-map-series](https://github.com/sindresorhus/p-map-series) - Map over promises serially
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- [p-queue](https://github.com/sindresorhus/p-queue) - Promise queue with concurrency control
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- [More…](https://github.com/sindresorhus/promise-fun)
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---
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<div align="center">
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<b>
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<a href="https://tidelift.com/subscription/pkg/npm-p-map?utm_source=npm-p-map&utm_medium=referral&utm_campaign=readme">Get professional support for this package with a Tidelift subscription</a>
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</b>
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<br>
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<sub>
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Tidelift helps make open source sustainable for maintainers while giving companies<br>assurances about security, maintenance, and licensing for their dependencies.
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</sub>
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</div>
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