unenv provides polyfills to add Node.js compatibility for any JavaScript runtime, including browsers and edge workers.

• Nitro
• Nuxt
• Cloudflare
• ESM.sh

The defineEnv utility can generate a target environment configuration.

import { defineEnv } from "unenv";

const { env } = defineEnv({
  nodeCompat: true,
  npmShims: true,
  resolve: true,
  overrides: {},
  presets: [],
});

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

You can then integrate the env object with your build tool:

• nodeCompat: (default: true)
  • Add alias entries for Node.js builtins as <id> and node:<id>.
  • Add inject entries for Node.js globals global, Buffer, and process.
• npmShims: (default: false)
  • Add alias entries to replace npm packages like node-fetch with lighter shims.
• resolve: (default: false) Resolve config values to absolute paths.
• overrides: Additional overrides for env config.
• presets: Additional presets (for example @cloudflare/unenv-preset).

You can also directly import unenv/ polyfills:

unenv replaces Node.js built-in modules compatible with any runtime (view source).

• ✅ 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

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

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

(view source)

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"
  }
}

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

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