p-locate

Get the first fulfilled promise that satisfies the provided testing function

Think of it like an async version of Array#find.

Install

$ npm install p-locate

Usage

Here we find the first file that exists on disk, in array order.

import {pathExists} from 'path-exists';
import pLocate from 'p-locate';

const files = [
	'unicorn.png',
	'rainbow.png', // Only this one actually exists on disk
	'pony.png'
];

const foundPath = await pLocate(files, file => pathExists(file));

console.log(foundPath);
//=> 'rainbow.png'

The above is just an example. Use locate-path if you need this.

API

pLocate(input, tester, options?)

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.

input

Type: Iterable<Promise | unknown>

An iterable of promises/values to test.

tester(element)

Type: Function

This function will receive resolved values from input and is expected to return a Promise<boolean> or boolean.

options

Type: object

concurrency

Type: number
Default: Infinity
Minimum: 1

The number of concurrently pending promises returned by tester.

preserveOrder

Type: boolean
Default: true

Preserve input order when searching.

Disable this to improve performance if you don't care about the order.

Related

• p-map - Map over promises concurrently
• p-filter - Filter promises concurrently
• p-any - Wait for any promise to be fulfilled
• More…

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