https://github.com/dcodeio/esm2umd

Transforms ESM to UMD, i.e. to use ESM by default with UMD as a legacy fallback.
https://github.com/dcodeio/esm2umd

esmodules javascript

Last synced: 2 months ago
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Transforms ESM to UMD, i.e. to use ESM by default with UMD as a legacy fallback.

• Host: GitHub
• URL: https://github.com/dcodeio/esm2umd
• Owner: dcodeIO
• Created: 2020-06-04T00:27:12.000Z (over 4 years ago)
• Default Branch: main
• Last Pushed: 2023-01-07T12:45:26.000Z (almost 2 years ago)
• Last Synced: 2024-09-14T13:27:26.649Z (4 months ago)
• Topics: esmodules, javascript
• Language: JavaScript
• Homepage:
• Size: 33.2 KB
• Stars: 4
• Watchers: 3
• Forks: 5
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
esm2umd

=======

Transforms ESM to UMD, i.e. to use ESM by default with UMD as a legacy fallback.

[![Build Status](https://img.shields.io/github/workflow/status/dcodeIO/esm2umd/Test/main?label=test&logo=github)](https://github.com/dcodeIO/esm2umd/actions?query=workflow%3ATest) [![Publish Status](https://img.shields.io/github/workflow/status/dcodeIO/esm2umd/Publish/main?label=publish&logo=github)](https://github.com/dcodeIO/esm2umd/actions?query=workflow%3APublish) [![npm](https://img.shields.io/npm/v/esm2umd.svg?label=npm&color=007acc&logo=npm)](https://www.npmjs.com/package/esm2umd)

Usage

-----

```

npx esm2umd MyModule esmFile.js > umdFile.js

```

`MyModule` is used as the name of the vanilla JS global.

If the module has a `default` export, it becomes the value obtained when `require`d.

API

---

Installation as a dependency is optional (pulls in megabytes of babel), but if so desired exposes the CLI as an API:

```js

import esm2umd from 'esm2umd'

const esmCode = '...'

const umdCode = esm2umd('ModuleName', esmCode)

```

Example

-------

ESM-first hybrid module with legacy fallback and prepublish build step.

**package.json**

```json

{

  "type": "module",

  "main": "./umd/index.js",

  "types": "index.d.ts",

  "exports": {

    "import": "./index.js",

    "require": "./umd/index.js"

  },

  "scripts": {

    "build": "npx esm2umd MyModule index.js > umd/index.js",

    "prepublishOnly": "npm run build"

  }

}

```

Treat .js files in `umd/` as CommonJS.

**umd/package.json**

```json

{

  "type": "commonjs"

}

```

Keep the generated artifact out of version control to avoid PRs against it.

**.gitignore**

```

umd/index.js

```

For typings, if there is a `default` export, stick to the "old" format for compatibility.

**index.d.ts**

```ts

export = MyModule;

```