# Is array.prototype.flatmap ESM-only? Can you require() it?

> array.prototype.flatmap@1.3.3 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

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

Last verified Sep 9, 2026 against array.prototype.flatmap@1.3.3.

array.prototype.flatmap ships CommonJS only. require("array.prototype.flatmap") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4. import "array.prototype.flatmap" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

## What to do

1. require("array.prototype.flatmap") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4.
2. From ES modules use the default import: import arrayPrototypeFlatmap from "array.prototype.flatmap"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/array.prototype.flatmap

## Facts

- Latest: 1.3.3 (Dec 16, 2024)
- Module format: CommonJS
- Last CommonJS version: 1.3.3
- TypeScript types: @types/array.prototype.flatmap
- Node engines: >= 0.4
- Weekly downloads: 63.2M
- License: MIT

## Runtime test results for array.prototype.flatmap@1.3.3

Installed and executed on Sep 9, 2026 with require("array.prototype.flatmap") from a CommonJS file and import "array.prototype.flatmap" from an ES module.

| Runtime | require("array.prototype.flatmap") | import "array.prototype.flatmap" |
|---|---|---|
| Node.js 18 | works | works |
| Node.js 20 | works | works |
| Node.js 22 | works | works |
| Node.js 24 | works | works |
| Node.js 26 | works | works |
| Bun 1.4.0 | works | works |

## How to import array.prototype.flatmap

ES modules:

```js
import arrayPrototypeFlatmap from "array.prototype.flatmap";
```

CommonJS:

```js
const arrayPrototypeFlatmap = require("array.prototype.flatmap");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (14 versions; the newest 14 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 1.3.3 | CommonJS | Oct 1, 2017 |

## Frequently asked

**Is array.prototype.flatmap ESM-only?**

array.prototype.flatmap@1.3.3 is a CommonJS package. array.prototype.flatmap ships CommonJS only. require("array.prototype.flatmap") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4. import "array.prototype.flatmap" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

**Can I import array.prototype.flatmap with ES module syntax?**

Yes. import arrayPrototypeFlatmap from "array.prototype.flatmap" works in Node.js and Bun because they support importing CommonJS modules. Named imports work only when Node.js can statically detect the exports.

**Does array.prototype.flatmap work in Bun?**

Yes. import "array.prototype.flatmap" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does array.prototype.flatmap ship TypeScript types?**

Not bundled. Install the community types with "npm install -D @types/array.prototype.flatmap".

## Links

- [array.prototype.flatmap on npm](https://www.npmjs.com/package/array.prototype.flatmap)
- [Source repository](https://github.com/es-shims/Array.prototype.flatMap)
- [HTML version](https://canirequire.com/package/array.prototype.flatmap/)
- [JSON version](https://canirequire.com/package/array.prototype.flatmap.json)

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