# array.prototype.flatmap

> An ES2019 spec-compliant `Array.prototype.flatMap` shim/polyfill/replacement that works as far down as ES3.

Latest version **1.3.3** (published 2024-12-16) · MIT license · 0 weekly downloads

> **Native alternative:** Array.prototype.flatMap — Use native JavaScript (Node 11.0.0+) (https://developer.mozilla.orgGlobal_Objects/Array/flatMap)

## Install

```sh
npm install array.prototype.flatmap
pnpm add array.prototype.flatmap
yarn add array.prototype.flatmap
bun add array.prototype.flatmap
```

## Health

**Score 43/100 (D)** — status: stable.

Positive: has types package; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: stale.

## Facts

| | |
|---|---|
| Version | 1.3.3 |
| Published | 2024-12-16 |
| First published | 2017-10-01 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | separate (@types/array.prototype.flatmap) |
| Module format | CommonJS |
| Node | >= 0.4 |
| Dependencies | 4 |
| Unpacked size | 20.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 33 |
| Author | Jordan Harband |
| Maintainers | ljharb |
| Keywords | Array.prototype.flatMap, flatMap, array, ESnext, shim, polyfill, flatten, Array.prototype.flatten, es-shim API |

## Links

- npm: https://www.npmjs.com/package/array.prototype.flatmap
- Repository: https://github.com/es-shims/Array.prototype.flatMap
- Homepage: https://github.com/es-shims/Array.prototype.flatMap#readme
- Issues: https://github.com/es-shims/Array.prototype.flatMap/issues
- Funding: https://github.com/sponsors/ljharb
- npm.io page: https://npm.io/package/array.prototype.flatmap

## Dependencies (4)

- [call-bind](https://npm.io/package/call-bind.md) ^1.0.8
- [es-abstract](https://npm.io/package/es-abstract.md) ^1.23.5
- [define-properties](https://npm.io/package/define-properties.md) ^1.2.1
- [es-shim-unscopables](https://npm.io/package/es-shim-unscopables.md) ^1.0.2

## Recent versions

- 1.3.3 (latest) — 2024-12-16
- 1.3.2 — 2023-09-07
- 1.3.1 — 2022-11-03
- 1.3.0 — 2022-04-11
- 1.2.5 — 2021-10-01
- 1.2.4 — 2020-11-18
- 1.2.3 — 2019-12-12
- 1.2.2 — 2019-10-11
- 1.2.1 — 2018-02-24
- 1.2.0 — 2018-01-19
- 1.1.1 — 2017-11-29
- 1.1.0 — 2017-10-04
- 1.0.1 — 2017-10-02
- 1.0.0 — 2017-10-01

## README

# array.prototype.flatmap <sup>[![Version Badge][npm-version-svg]][package-url]</sup>

[![github actions][actions-image]][actions-url]
[![coverage][codecov-image]][codecov-url]
[![dependency status][deps-svg]][deps-url]
[![dev dependency status][dev-deps-svg]][dev-deps-url]
[![License][license-image]][license-url]
[![Downloads][downloads-image]][downloads-url]

[![npm badge][npm-badge-png]][package-url]

An ES2019 spec-compliant `Array.prototype.flatMap` shim/polyfill/replacement that works as far down as ES3.

This package implements the [es-shim API](https://github.com/es-shims/api) interface. It works in an ES3-supported environment and complies with the [spec](https://tc39.es/ecma262/#sec-array.prototype.flatmap).

Because `Array.prototype.flatMap` depends on a receiver (the `this` value), the main export takes the array to operate on as the first argument.

## Getting started

```sh
npm install --save array.prototype.flatmap
```

## Usage/Examples

```js
var flatMap = require('array.prototype.flatmap');
var assert = require('assert');

var arr = [1, [2], [], 3];

var results = flatMap(arr, function (x, i) {
	assert.equal(x, arr[i]);
	return x;
});

assert.deepEqual(results, [1, 2, 3]);
```

```js
var flatMap = require('array.prototype.flatmap');
var assert = require('assert');
/* when Array#flatMap is not present */
delete Array.prototype.flatMap;
var shimmedFlatMap = flatMap.shim();

var mapper = function (x) { return [x, 1]; };

assert.equal(shimmedFlatMap, flatMap.getPolyfill());
assert.deepEqual(arr.flatMap(mapper), flatMap(arr, mapper));
```

```js
var flatMap = require('array.prototype.flatmap');
var assert = require('assert');
/* when Array#flatMap is present */
var shimmedIncludes = flatMap.shim();

var mapper = function (x) { return [x, 1]; };

assert.equal(shimmedIncludes, Array.prototype.flatMap);
assert.deepEqual(arr.flatMap(mapper), flatMap(arr, mapper));
```

## Tests
Simply clone the repo, `npm install`, and run `npm test`

[package-url]: https://npmjs.org/package/array.prototype.flatmap
[npm-version-svg]: https://versionbadg.es/es-shims/Array.prototype.flatMap.svg
[deps-svg]: https://david-dm.org/es-shims/Array.prototype.flatMap.svg
[deps-url]: https://david-dm.org/es-shims/Array.prototype.flatMap
[dev-deps-svg]: https://david-dm.org/es-shims/Array.prototype.flatMap/dev-status.svg
[dev-deps-url]: https://david-dm.org/es-shims/Array.prototype.flatMap#info=devDependencies
[npm-badge-png]: https://nodei.co/npm/array.prototype.flatmap.png?downloads=true&stars=true
[license-image]: https://img.shields.io/npm/l/array.prototype.flatmap.svg
[license-url]: LICENSE
[downloads-image]: https://img.shields.io/npm/dm/array.prototype.flatmap.svg
[downloads-url]: https://npm-stat.com/charts.html?package=array.prototype.flatmap
[codecov-image]: https://codecov.io/gh/es-shims/Array.prototype.flatMap/branch/main/graphs/badge.svg
[codecov-url]: https://app.codecov.io/gh/es-shims/Array.prototype.flatMap/
[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/es-shims/Array.prototype.flatMap
[actions-url]: https://github.com/es-shims/Array.prototype.flatMap/actions

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