87 lines
2 KiB
Markdown
87 lines
2 KiB
Markdown
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# p-locate [](https://travis-ci.org/sindresorhus/p-locate)
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> Get the first fulfilled promise that satisfies the provided testing function
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Think of it like an async version of [`Array#find`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/find).
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## Install
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```
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$ npm install --save p-locate
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```
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## Usage
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Here we find the first file that exists on disk, in array order.
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```js
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const pathExists = require('path-exists');
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const pLocate = require('p-locate');
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const files = [
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'unicorn.png',
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'rainbow.png', // only this one actually exists on disk
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'pony.png'
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];
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pLocate(files, file => pathExists(file)).then(foundPath => {
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console.log(foundPath);
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//=> 'rainbow'
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});
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```
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*The above is just an example. Use [`locate-path`](https://github.com/sindresorhus/locate-path) if you need this.*
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## API
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### pLocate(input, tester, [options])
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Returns a `Promise` that is fulfilled when `tester` resolves to `true` or the iterable is done, or rejects if any of the promises reject. The fulfilled value is the current iterable value or `undefined` if `tester` never resolved to `true`.
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#### input
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Type: `Iterable<Promise|any>`
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#### tester(element)
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Type: `Function`
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Expected to return a `Promise<boolean>` or boolean.
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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 `tester`.
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##### preserveOrder
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Type: `boolean`<br>
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Default: `true`
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Preserve `input` order when searching.
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Disable this to improve performance if you don't care about the order.
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## Related
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- [p-map](https://github.com/sindresorhus/p-map) - Map over promises concurrently
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- [p-filter](https://github.com/sindresorhus/p-filter) - Filter promises concurrently
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- [p-any](https://github.com/sindresorhus/p-any) - Wait for any promise to be fulfilled
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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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