https://github.com/addaleax/gen-esm-wrapper

Generate ESM wrapper files for CommonJS modules
https://github.com/addaleax/gen-esm-wrapper

Last synced: about 2 months ago
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Generate ESM wrapper files for CommonJS modules

• Host: GitHub
• URL: https://github.com/addaleax/gen-esm-wrapper
• Owner: addaleax
• License: mit
• Created: 2020-05-03T05:34:09.000Z (about 4 years ago)
• Default Branch: master
• Last Pushed: 2021-09-21T16:07:45.000Z (almost 3 years ago)
• Last Synced: 2024-05-04T21:41:38.619Z (about 2 months ago)
• Language: JavaScript
• Size: 59.6 KB
• Stars: 131
• Watchers: 4
• Forks: 8
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# gen-esm-wrapper

Generate ESM wrapper files for CommonJS modules

This CLI tool makes it easier for module authors to support both ES modules

and CommonJS modules for Node.js.

It looks at the exports of an existing CommonJS module, and creates

an ES module wrapper file that makes the exports available as named exports.

For example, if you are in the root of your npm package, you can use

```bash

gen-esm-wrapper . path/to/wrapper/output.mjs

```

to create a wrapper file, and add

```js

  ...

  "exports": {

    ".": {

      "require": "./",

      "import": "./path/to/wrapper/output.mjs"

    },

    "./": "./"

  }

  ...

```

to your `package.json` in order to make your module available as a dual

ESM/CJS package.

The command can also be added as a build step before publishing.

The above example `"exports":` key can be simplified to

```js

  ...

  "exports": {

    "require": "./",

    "import": "./path/to/wrapper/output.mjs"

  }

  ...

```

if there are no other JavaScript files that can be required from the package

besides the main entry point (e.g. a file named `foo.js` that can be loaded

through `require('package/foo')`), or if you are okay with breaking

`require()` calls to those modules. This is the recommended approach for new

modules that are being published for the first time.

## Example project

There is a minimal example in the `example-project` directory in this

repository. This is its package.json:

```js

{

  "name": "example-project",

  "version": "1.0.0",

  "description": "Example project for gen-esm-wrapper",

  "main": "index.js",

  "exports": {

    ".": {

      "require": "./index.js",

      "import": "./dist/output.mjs"

    },

    "./": "./"

  },

  "scripts": {

    "test": "npm run build && node ./dist/output.mjs",

    "build": "gen-esm-wrapper . ./dist/output.mjs",

    "prepack": "npm run build"

  },

  "devDependencies": {

    "gen-esm-wrapper": "^1.0.4"

  }

}

```