# Is merge2 ESM-only? Can you require() it?

> merge2@1.4.1 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Merge multiple streams into one stream in sequence or parallel.

Last verified Sep 9, 2026 against merge2@1.4.1.

merge2 ships CommonJS only. require("merge2") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 8. import "merge2" 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("merge2") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 8.
2. From ES modules use the default import: import merge2 from "merge2"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/merge2

## Facts

- Latest: 1.4.1 (Jun 3, 2020)
- Module format: CommonJS
- Last CommonJS version: 1.4.1
- TypeScript types: @types/merge2
- Node engines: >= 8
- Weekly downloads: 83.6M
- License: MIT

## Runtime test results for merge2@1.4.1

Installed and executed on Sep 9, 2026 with require("merge2") from a CommonJS file and import "merge2" from an ES module.

| Runtime | require("merge2") | import "merge2" |
|---|---|---|
| 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 merge2

ES modules:

```js
import merge2 from "merge2";
```

CommonJS:

```js
const merge2 = require("merge2");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (23 versions; the newest 23 shown).

| Versions | Format | First published |
|---|---|---|
| 0.2.0 – 1.4.1 | CommonJS | Oct 19, 2014 |

## Frequently asked

**Is merge2 ESM-only?**

merge2@1.4.1 is a CommonJS package. merge2 ships CommonJS only. require("merge2") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 8. import "merge2" 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 merge2 with ES module syntax?**

Yes. import merge2 from "merge2" 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 merge2 work in Bun?**

Yes. import "merge2" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does merge2 ship TypeScript types?**

Not bundled. Install the community types with "npm install -D @types/merge2".

## Links

- [merge2 on npm](https://www.npmjs.com/package/merge2)
- [Source repository](https://github.com/teambition/merge2)
- [HTML version](https://canirequire.com/package/merge2/)
- [JSON version](https://canirequire.com/package/merge2.json)

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