# dual-publish

**Repository Path**: mirrors_ai/dual-publish

## Basic Information

- **Project Name**: dual-publish
- **Description**: Publish JS project as dual ES modules and CommonJS package to npm
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-01-26
- **Last Updated**: 2026-05-17

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 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>


## Limits

* We recommend to avoid default export because of [bug in webpack].
* Every JS file should be in own dir. `lib/index.js` instead of `lib.js`.
  We need it to put `package.json` with `module`.

[bug in webpack]: https://github.com/webpack/webpack/issues/6584


## Usage

1. Take a normal CommonJS project with `require()` and `module.exports =`.
2. Because of [bug in webpack] we recommend to use only named exports:

   ```js
   const NAME = 'a'
   function change {
     …
   }

   module.exports = { NAME, change }
   ```
3. Move all files into separated dirs. Rename `lib.js` to `lib/index.js`.
   Old `require('./lib')` will work.
4. Add `dual-publish` to the project:

   ```sh
   npm i --save-dev dual-publish
   ```
5. Test the result by calling `npx dual-publish --check`.
   It will create a folder in your project with converted files.
   Review them manually.
6. Publish your project with `npx dual-publish` instead of `npm publish`.

   ```sh
   npx dual-publish
   ```