# array.prototype.findlastindex

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

Latest version **1.2.6** (published 2025-03-14) · MIT license · 0 weekly downloads

## Install

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

## Health

**Score 30/100 (F)** — status: maintenance-mode.

Positive: esm support; no vulnerabilities.

Warnings: low downloads; no types.

Negative: stale; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.2.6 |
| Published | 2025-03-14 |
| First published | 2021-07-14 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | ESM + CommonJS |
| Node | >= 0.4 |
| Dependencies | 7 |
| Unpacked size | 29.8 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 3 |
| Author | Jordan Harband |
| Maintainers | ljharb |
| Keywords | Array.prototype.findLastIndex, find, findLast, findLastIndex, array, ESnext, shim, polyfill, last, es-shim API |

## Links

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

## Dependencies (7)

- [call-bind](https://npm.io/package/call-bind.md) ^1.0.8
- [es-errors](https://npm.io/package/es-errors.md) ^1.3.0
- [call-bound](https://npm.io/package/call-bound.md) ^1.0.4
- [es-abstract](https://npm.io/package/es-abstract.md) ^1.23.9
- [es-object-atoms](https://npm.io/package/es-object-atoms.md) ^1.1.1
- [define-properties](https://npm.io/package/define-properties.md) ^1.2.1
- [es-shim-unscopables](https://npm.io/package/es-shim-unscopables.md) ^1.1.0

## Recent versions

- 1.2.6 (latest) — 2025-03-14
- 1.2.5 — 2024-03-19
- 1.2.4 — 2024-02-06
- 1.2.3 — 2023-08-30
- 1.2.2 — 2022-11-03
- 1.2.1 — 2022-04-11
- 1.2.0 — 2022-04-11
- 1.1.1 — 2021-10-01
- 1.1.0 — 2021-08-07
- 1.0.0 — 2021-07-14

## README

# array.prototype.findlastindex <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 ESnext spec-compliant `Array.prototype.findLastIndex` 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 proposed [spec](https://tc39.es/proposal-array-find-from-last).

Because `Array.prototype.findLastIndex` 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.findlastindex
```

## Usage/Examples

```js
var findLastIndex = require('array.prototype.findlastindex');
var assert = require('assert');

var arr = [1, [2], [], 3, [[4]]];
var isNumber = function (x) { return typeof x === 'number' };

assert.deepEqual(findLastIndex(arr, isNumber), 3);
```

```js
var findLastIndex = require('array.prototype.findlastindex');
var assert = require('assert');
/* when Array#findLastIndex is not present */
delete Array.prototype.findLastIndex;
var shimmed = findLastIndex.shim();

assert.equal(shimmed, findLastIndex.getPolyfill());
assert.deepEqual(arr.findLastIndex(isNumber), findLastIndex(arr, isNumber));
```

```js
var findLastIndex = require('array.prototype.findlastindex');
var assert = require('assert');
/* when Array#findLastIndex is present */
var shimmed = findLastIndex.shim();

assert.equal(shimmed, Array.prototype.findLastIndex);
assert.deepEqual(arr.findLastIndex(isNumber), findLastIndex(arr, isNumber));
```

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

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

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