1 | # p-locate [![Build Status](https://travis-ci.org/sindresorhus/p-locate.svg?branch=master)](https://travis-ci.org/sindresorhus/p-locate)
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2 |
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3 | > Get the first fulfilled promise that satisfies the provided testing function
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4 |
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5 | 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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6 |
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7 |
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8 | ## Install
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9 |
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10 | ```
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11 | $ npm install p-locate
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12 | ```
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13 |
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14 |
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15 | ## Usage
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16 |
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17 | Here we find the first file that exists on disk, in array order.
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18 |
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19 | ```js
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20 | const pathExists = require('path-exists');
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21 | const pLocate = require('p-locate');
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22 |
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23 | const files = [
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24 | 'unicorn.png',
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25 | 'rainbow.png', // Only this one actually exists on disk
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26 | 'pony.png'
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27 | ];
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28 |
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29 | (async () => {
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30 | const foundPath = await pLocate(files, file => pathExists(file));
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31 |
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32 | console.log(foundPath);
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33 | //=> 'rainbow'
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34 | })();
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35 | ```
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36 |
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37 | *The above is just an example. Use [`locate-path`](https://github.com/sindresorhus/locate-path) if you need this.*
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38 |
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39 |
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40 | ## API
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41 |
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42 | ### pLocate(input, tester, [options])
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43 |
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44 | 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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45 |
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46 | #### input
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47 |
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48 | Type: `Iterable<Promise | unknown>`
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49 |
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50 | An iterable of promises/values to test.
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51 |
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52 | #### tester(element)
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53 |
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54 | Type: `Function`
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55 |
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56 | This function will receive resolved values from `input` and is expected to return a `Promise<boolean>` or `boolean`.
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57 |
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58 | #### options
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59 |
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60 | Type: `Object`
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61 |
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62 | ##### concurrency
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63 |
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64 | Type: `number`<br>
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65 | Default: `Infinity`<br>
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66 | Minimum: `1`
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67 |
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68 | Number of concurrently pending promises returned by `tester`.
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69 |
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70 | ##### preserveOrder
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71 |
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72 | Type: `boolean`<br>
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73 | Default: `true`
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74 |
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75 | Preserve `input` order when searching.
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76 |
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77 | Disable this to improve performance if you don't care about the order.
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78 |
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79 |
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80 | ## Related
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81 |
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82 | - [p-map](https://github.com/sindresorhus/p-map) - Map over promises concurrently
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83 | - [p-filter](https://github.com/sindresorhus/p-filter) - Filter promises concurrently
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84 | - [p-any](https://github.com/sindresorhus/p-any) - Wait for any promise to be fulfilled
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85 | - [More…](https://github.com/sindresorhus/promise-fun)
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86 |
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87 |
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88 | ## License
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89 |
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90 | MIT © [Sindre Sorhus](https://sindresorhus.com)
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