unjs
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.
[!NOTE] You are on the legacy (v1) branch. Checkout main branch for latest development.
Install
# Using npm
npm i -D unenv
# Using yarn
yarn add --dev unenv
# Using pnpm
pnpm add -D unenvUsage
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
Suitable to convert universal libraries working in Node.js.
- Add supports for global
fetchAPI - Set Node.js built-ins as externals
import { env, nodeless } from "unenv";
const envConfig = env(node, {});nodeless
Suitable to transform libraries made for Node.js to run in other JavaScript runtimes.
import { env, nodeless } from "unenv";
const envConfig = env(nodeless, {});deno
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
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_compatcompatibility 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.
| Package | Status | Source |
|---|---|---|
| npm/consola | Use native console |
unenv/runtime/npm/consola |
| npm/cross-fetch | Use native fetch |
unenv/runtime/npm/cross-fetch |
| npm/debug | Mocked with console.debug |
unenv/runtime/npm/debug |
| npm/fsevents | Mocked | unenv/runtime/npm/fsevents |
| npm/inherits | Inlined | unenv/runtime/npm/inherits |
| npm/mime-db | Minimized | unenv/runtime/npm/mime-db |
| npm/mime | Minimized | unenv/runtime/npm/mime |
| npm/node-fetch | Use native fetch |
unenv/runtime/npm/node-fetch |
| npm/whatwg-url | Use native URL |
unenv/runtime/npm/whatwg-url |
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("node:os");
if (os.platform() === "windows") {
/* do some fix */
}
module.exports = function main() {
return "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