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

> clsx@2.1.1 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

A tiny (239B) utility for constructing className strings conditionally.

Last verified Sep 9, 2026 against clsx@2.1.1.

clsx publishes both a CommonJS entry and a native ESM entry (ESM added in 2.0.0). require("clsx") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6. import "clsx" works alongside it.

## What to do

1. Nothing to change. require("clsx") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6. import * as clsx from "clsx" works alongside it; use named imports for what the ESM entry exports.
2. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 2.1.1 (Apr 23, 2024)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 2.1.1
- Native ESM since: 2.0.0
- TypeScript types: bundled
- Node engines: >=6
- Weekly downloads: 105.5M
- License: MIT

## Runtime test results for clsx@2.1.1

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

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

ES modules:

```js
import * as clsx from "clsx";
```

Namespace import shown because the ESM entry may have no default export; use named imports for what it exports.

CommonJS:

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

## 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 |
|---|---|---|
| 2.0.0 – 2.1.1 | Dual (CommonJS + ESM) | Jul 15, 2023 |
| 0.0.1 – 1.2.1 | CommonJS | Dec 24, 2018 |

## Frequently asked

**Is clsx ESM-only?**

clsx@2.1.1 ships CommonJS and ESM builds. clsx publishes both a CommonJS entry and a native ESM entry (ESM added in 2.0.0). require("clsx") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6. import "clsx" works alongside it.

**Can I require clsx?**

Yes. clsx ships a CommonJS entry alongside the native ESM entry. require("clsx") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6.

**Does clsx work in Bun?**

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

**Does clsx ship TypeScript types?**

Yes. clsx bundles its own type declarations; no @types package is needed.

## Links

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

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