unenv

unenv provides a collection of Node.js and Web polyfills and mocking utilities with configurable presets for converting JavaScript code and libraries to be platform and runtime agnostic, working in any environment including Browsers, Workers, Node.js, Cloudflare Workers, Deno.

Unenv is used by Nitro and Nuxt today.

Note

You are on the development (v2) branch. Check out v1 for the current release.

Install

# ✨ Auto-detect
npx nypm install -D unenv

# npm
npm install -D unenv

# yarn
yarn add -D unenv

# pnpm
pnpm install -D unenv

# bun
bun install -D unenv

Usage

Using env utility and built-in presets, unenv will provide an abstract configuration that can be used in bundlers (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, node } 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 Node.js built-in modules compatible with any runtime.

• ✅ node:assert
• ✅ node:assert/strict
• ✅ node:async_hooks
• ✅ node:buffer
• ✅ node:child_process
• ✅ node:cluster
• ✅ node:console
• ✅ node:constants
• ✅ node:crypto
• ✅ node:dgram
• ✅ node:diagnostics_channel
• ✅ node:dns
• ✅ node:dns/promises
• ✅ node:domain
• ✅ node:events
• ✅ node:fs
• ✅ node:fs/promises
• ✅ node:http
• ✅ node:http2
• ✅ node:https
• ✅ node:inspector
• 🚧 node:inspector/promises
• ✅ node:module
• ✅ node:net
• ✅ node:os
• ✅ node:path
• ✅ node:path/posix
• ✅ node:path/win32
• ✅ node:perf_hooks
• ✅ node:process
• ✅ node:punycode
• ✅ node:querystring
• ✅ node:readline
• ✅ node:readline/promises
• 🚧 node:repl
• 🚧 node:stream
• ✅ node:stream/consumers
• ✅ node:stream/promises
• ✅ node:stream/web
• ✅ node:string_decoder
• ✅ node:sys
• ✅ node:timers
• ✅ node:timers/promises
• ✅ node:tls
• ✅ node:trace_events
• ✅ node:tty
• ✅ node:url
• ✅ node:util
• ✅ node:util/types
• ✅ node:v8
• ✅ node:vm
• ✅ node:wasi
• ✅ node:worker_threads
• 🚧 node:zlib

(view source)

Package replacements

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

(view source)

Manual mocking utils

// Magic proxy to replace any unknown API
import MockProxy from "unenv/runtime/mock/proxy";

// You can also create named mocks
const lib = MockProxy.__createMock__("lib", {
  /* overrides */
});

(view source)

Other polyfills

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

Nightly release channel

You can use the nightly release channel to try the latest changes in the main branch via unenv-nightly.

If directly using unenv in your project:

{
  "devDependencies": {
    "unenv": "npm:unenv-nightly"
  }
}

If using unenv via another tool (Nuxt or Nitro) in your project:

{
  "resolutions": {
    "unenv": "npm:unenv-nightly"
  }
}

License

Published under the MIT license. Made by @pi0 and community 💛

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