86 lines
2.2 KiB
Markdown
86 lines
2.2 KiB
Markdown
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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('sindresorhus'), //=> Promise
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'ava.li',
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'todomvc.com',
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'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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//=> ['http://sindresorhus.com/', 'http://ava.li/', 'http://todomvc.com/', 'http://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|any>`
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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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## 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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## License
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MIT © [Sindre Sorhus](https://sindresorhus.com)
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