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

> postcss-js@5.1.0 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

PostCSS for CSS-in-JS and styles in JS objects

Last verified Sep 9, 2026 against postcss-js@5.1.0.

postcss-js publishes both a CommonJS entry and a native ESM entry (ESM added in 3.0.0). require("postcss-js") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js ^20 || ^22 || >= 24. import "postcss-js" works alongside it.

## What to do

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

## Facts

- Latest: 5.1.0 (Feb 13, 2026)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 5.1.0
- Native ESM since: 3.0.0
- TypeScript types: bundled
- Node engines: ^20 || ^22 || >= 24
- Weekly downloads: 33.1M
- License: MIT

## Runtime test results for postcss-js@5.1.0

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

| Runtime | require("postcss-js") | import "postcss-js" |
|---|---|---|
| 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 postcss-js

ES modules:

```js
import * as postcssJs from "postcss-js";
```

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

CommonJS:

```js
const postcssJs = require("postcss-js");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (24 versions; the newest 24 shown).

| Versions | Format | First published |
|---|---|---|
| 3.0.0 – 5.1.0 | Dual (CommonJS + ESM) | Sep 15, 2020 |
| 0.1.0 – 2.0.3 | CommonJS | Oct 15, 2015 |

## Frequently asked

**Is postcss-js ESM-only?**

postcss-js@5.1.0 ships CommonJS and ESM builds. postcss-js publishes both a CommonJS entry and a native ESM entry (ESM added in 3.0.0). require("postcss-js") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js ^20 || ^22 || >= 24. import "postcss-js" works alongside it.

**Can I require postcss-js?**

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

**Does postcss-js work in Bun?**

Yes. import "postcss-js" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does postcss-js ship TypeScript types?**

Yes. postcss-js bundles its own type declarations; no @types package is needed.

## Links

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

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