# p-filter

> Filter promises concurrently

Latest version **4.1.0** (published 2023-12-27) · MIT license · 0 weekly downloads

## Install

```sh
npm install p-filter
pnpm add p-filter
yarn add p-filter
bun add p-filter
```

## Health

**Score 40/100 (D)** — status: abandoned.

Positive: has types; esm support; no vulnerabilities; high quality score.

Warnings: low downloads.

Negative: abandoned.

## Facts

| | |
|---|---|
| Version | 4.1.0 |
| Published | 2023-12-27 |
| First published | 2016-10-21 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM |
| Node | >=18 |
| Dependencies | 1 |
| Unpacked size | 8 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 82 |
| Author | Sindre Sorhus |
| Maintainers | sindresorhus |
| Keywords | promise, filter, collection, iterable, iterator, fulfilled, async, await, promises, concurrently, concurrency, parallel |

## Links

- npm: https://www.npmjs.com/package/p-filter
- Repository: https://github.com/sindresorhus/p-filter
- Homepage: https://github.com/sindresorhus/p-filter#readme
- Issues: https://github.com/sindresorhus/p-filter/issues
- Funding: https://github.com/sponsors/sindresorhus
- npm.io page: https://npm.io/package/p-filter

## Dependencies (1)

- [p-map](https://npm.io/package/p-map.md) ^7.0.1

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## Recent versions

- 4.1.0 (latest) — 2023-12-27
- 4.0.0 — 2023-12-22
- 3.0.0 — 2021-08-12
- 2.1.0 — 2019-04-04
- 2.0.0 — 2019-03-13
- 1.0.0 — 2016-10-21

## README

# p-filter

> Filter promises concurrently

Useful when you need to run promise-returning & async functions multiple times with different inputs concurrently and get a filtered down result.

## Install

```sh
npm install p-filter
```

## Usage

```js
import pFilter from 'p-filter';
import getWeather from 'get-weather'; // Not a real module

const places = [
	getCapital('Norway').then(info => info.name),
	'Bangkok, Thailand',
	'Berlin, Germany',
	'Tokyo, Japan',
];

const filterer = async place => {
	const weather = await getWeather(place);
	return weather.temperature > 30;
};

const result = await pFilter(places, filterer);

console.log(result);
//=> ['Bangkok, Thailand']
```

## API

### pFilter(input, filterer, options?)

Returns a `Promise` that is fulfilled when all promises in `input` and ones returned from `filterer` are fulfilled, or rejects if any of the promises reject. The fulfilled value is an `Array` of the fulfilled values returned from `filterer` in `input` order.

#### input

Type: `Iterable<Promise<unknown> | unknown>`

Iterated over concurrently in the `filterer` function.

#### filterer(element, index)

Type: `Function`

The filterer function that decides whether an element should be included into result. Expected to return `boolean | Promise<boolean>`.

#### options

Type: `object`

See the [`p-map` options](https://github.com/sindresorhus/p-map#options).

##### concurrency

Type: `number`\
Default: `Infinity`\
Minimum: `1`

The number of concurrently pending promises returned by `filterer`.

### pFilterIterable(iterable, filterer, options?)

Returns an async iterable that iterates over the promises in `iterable` and ones returned from `filterer` concurrently, calling `filterer` for each element.

```js
import {pFilterIterable} from 'p-filter';
import getWeather from 'get-weather'; // Not a real module

async function * getPlaces() {
	const name = await getCapital('Norway');

	yield name;
	yield 'Bangkok, Thailand';
	yield 'Berlin, Germany';
	yield 'Tokyo, Japan';
}

const places = getPlaces();

const filterer = async place => {
	const weather = await getWeather(place);
	return weather.temperature > 30;
};

for await (const element of pFilterIterable(places, filterer)) {
	console.log(element);
}
//=> ['Bangkok, Thailand']
```

#### iterable

Type: `Iterable<Promise<unknown> | unknown>`

Iterated over concurrently in the `filterer` function.

#### filterer(element, index)

Type: `Function`

The filterer function that decides whether an element should be included into result. Expected to return `boolean | Promise<boolean>`.

#### options

Type: `object`

See the [`p-map` options](https://github.com/sindresorhus/p-map#options).

##### concurrency

Type: `number`\
Default: `Infinity`\
Minimum: `1`

The number of concurrently pending promises returned by `filterer`.

## Related

- [p-locate](https://github.com/sindresorhus/p-locate) - Get the first fulfilled promise that satisfies the provided testing function
- [p-map](https://github.com/sindresorhus/p-map) - Map over promises concurrently
- [p-times](https://github.com/sindresorhus/p-times) - Run promise-returning & async functions a specific number of times concurrently
- [More…](https://github.com/sindresorhus/promise-fun)

---
_Source: https://npm.io/package/p-filter · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._