Unenv is a framework agnostic system that allows converting JavaScript code to be platform agnostic and working in any environment including Browsers, Workers, Node.js or pure JavaScript runtime.

# Using npm
npm i -D unenv

# Using yarn
yarn add --dev unenv

Using env utility and builtin presets ( and nodeless), unenv will provide an abstract config that can be used in building pipelines (rollup.js, webpack, etc)

import { env, node, nodeless } from 'unenv'

const { alias, inject, polyfill, external } = env(...presets)

Suitable to convert universal libraries working in Node.js. (preset)

• Add support for global fetch API
• Set Node.js built-ins as externals

Using this preset, we can convert a code that is depending on Node.js to work anywhere else.

Unenv provides a replacement for all Node.js built-ins for cross-platform compatiblity.

Unenv provides a replacement for common npm packages for cross platform compatibility.

import MockProxy from 'unenv/runtime/mock/proxy'

console.log(MockProxy().foo.bar()[0])

Above package doesn't works outside of Node.js and neither we need any platform specific logic! When aliasing os to mock/proxy-cjs, it will be auto mocked using a Proxy Object which can be recursively traversed like an Object, called like a Function, Iterated like an Array, or instantiated like a Class.

We use this proxy for auto mocking unimplemented internals. Imagine a packages does this:

const os = require('os')
if (os.platform() === 'windows') { /* do some fix */ }
module.exports = () => 'Hello world'

By aliasing os to unenv/runtime/mock/proxy-cjs, code will be compatible in other platforms.

Please check ./src/runtime to discover other polyfills.

MIT