# Dual Publish

Publish JS project as dual ES modules and CommonJS package to npm.

* Tested on [projects] with **16M downloads per month**.
* [CI tests] with it works with **Node.js**, **browsers**, **React Native**,
  **bundlers** (webpack, Parcel, Rollup, or esbuild) and **CDNs** (like jspm).
* Does not change **line numbers in stacktrace** and keep sources **readable**.
* **No build step.** No need for separated `src/` and `dist/` dirs in repository.
  You will be able to test branch by installing version from GitHub like
  `npm i example@you/example#fix`.
* **Multiple files support**. Your user will be able to import separated files
  <br/>like `import { nanoid } from 'nanoid/async'`.
* Cleans npm package from development configs [before publishing].
* Supports `process.env.NODE_ENV` for development checks, which you want
  to remove in production JS bundle.

You write CommonJS in your npm library sources:

```js
// index.js
module.exports = { lib }
```

`npx dual-publish` compiles your library during publishing to npm:

```js
// index.js
export { lib }

// index.cjs
module.exports = { lib }

// package.json
{
  …
  "type": "module",
  "module": "index.js",
  "main": "index.cjs",
  "exports": {
    "require": "./index.cjs",
    "import": "./index.js"
  }
}
```

Now your library can be imported natively as ESM or CommonJS:

```js
// CommonJS
let { lib } = require('lib')

// ESM in Node.js, webpack, Parcel, and Rollup
import { lib } from 'lib'

// ESM in browser
import { lib } from 'https://cdn.jsdelivr.net/npm/lib/index.js'
```

[before publishing]: https://github.com/shashkovdanil/clean-publish/
[CI tests]: https://github.com/ai/dual-publish/blob/master/test/index.test.js
[projects]: https://github.com/search?l=JSON&q=%22dual-publish%22&type=Code

<a href="https://evilmartians.com/?utm_source=dual-publish">
  <img src="https://evilmartians.com/badges/sponsored-by-evil-martians.svg"
      alt="Sponsored by Evil Martians" width="236" height="54">
</a>


## Docs
Read full docs **[here](https://github.com/ai/dual-publish#readme)**.