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

> regexpu-core@6.4.0 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

regexpu’s core functionality (i.e. `rewritePattern(pattern, flag)`), capable of translating ES6 Unicode regular expressions to ES5.

Last verified Sep 9, 2026 against regexpu-core@6.4.0.

regexpu-core ships CommonJS only. require("regexpu-core") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "regexpu-core" 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("regexpu-core") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4.
2. From ES modules use the default import: import regexpuCore from "regexpu-core"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 6.4.0 (Sep 22, 2025)
- Module format: CommonJS
- Last CommonJS version: 6.4.0
- TypeScript types: bundled
- Node engines: >=4
- Weekly downloads: 43.0M
- License: MIT

## Runtime test results for regexpu-core@6.4.0

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

| Runtime | require("regexpu-core") | import "regexpu-core" |
|---|---|---|
| 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 regexpu-core

ES modules:

```js
import regexpuCore from "regexpu-core";
```

CommonJS:

```js
const regexpuCore = require("regexpu-core");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (53 versions; the newest 53 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 6.4.0 | CommonJS | Jan 11, 2016 |

## Frequently asked

**Is regexpu-core ESM-only?**

regexpu-core@6.4.0 is a CommonJS package. regexpu-core ships CommonJS only. require("regexpu-core") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "regexpu-core" 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 regexpu-core with ES module syntax?**

Yes. import regexpuCore from "regexpu-core" 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 regexpu-core work in Bun?**

Yes. import "regexpu-core" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does regexpu-core ship TypeScript types?**

Yes. regexpu-core bundles its own type declarations; no @types package is needed.

## Links

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

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