unenv

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

Install

 # Using npm
npm i -D unenv

# Using yarn
yarn add --dev unenv

# Using pnpm
pnpm add -D unenv

Usage

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

 import { env } from "unenv";

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

Note: You can provide as many presets as you want. unenv will merge them internally and the right-most preset has a higher priority.

Presets

node

(view source)

Suitable to convert universal libraries working in Node.js.

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

 import { env, nodeless } from "unenv";

const envConfig = env(node, {});

nodeless

(view source)

Suitable to transform libraries made for Node.js to run in other JavaScript runtimes.

 import { env, nodeless } from "unenv";

const envConfig = env(nodeless, {});

deno

(view source)

This preset can be used to extend nodeless to use Deno's Node.js API Compatibility (docs, docs).

[!WARNING]
This preset is experimental and behavior might change!

 import { env, nodeless, deno } from "unenv";

const envConfig = env(nodeless, deno, {});

cloudflare

(view source)

This preset can be used to extend nodeless to use Cloudflare Worker Node.js API Compatibility (docs).

[!WARNING]
This preset is experimental and behavior might change!

[!NOTE]
Make sure to enable nodejs_compat compatibility flag.

 import { env, nodeless, cloudflare } from "unenv";

const envConfig = env(nodeless, cloudflare, {});

vercel

This preset can be used to extend nodeless to use Vercel Edge Node.js API Compatibility (docs).

[!WARNING]
This preset is experimental and behavior might change!

 import { env, nodeless, vercel } from "unenv";

const envConfig = env(nodeless, vercel, {});

Built-in Node.js modules

unenv provides a replacement for all Node.js built-ins for cross-platform compatibility.

npm packages

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

Auto-mocking proxy

 import MockProxy from "unenv/runtime/mock/proxy";

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

The above package doesn't work 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 package 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, the code will be compatible with other platforms.

Other polyfills

To discover other polyfills, please check ./src/runtime.

License

MIT