npm package: @pi0/unenv
Description: `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.
Latest version: 1.9.0-rc.2

# 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

```bash
# 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](https://rollupjs.org), [webpack](https://webpack.js.org), etc.).

```js
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.

### `node` preset

Suitable to convert universal libraries working in Node.js.

- Add supports for global [`fetch` API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
- Set Node.js built-ins as externals

```js
import { env, nodeless } from "unenv";

const envConfig = env(node, {});
```

[(view `node` preset source)](./src/presets/node.ts)

### `nodeless` preset

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

```js
import { env, nodeless } from "unenv";

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

[(view `nodeless` preset source)](./src/presets/nodeless.ts)

### `deno` preset

**Note:** This preset is **experimental** and behavior can change!

This preset can be used to extend `nodeless` to use Deno's Node.js API Compatibility ([docs](https://docs.deno.com/runtime/manual/node/compatibility), [docs](https://docs.deno.com/deploy/api/runtime-node)).

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

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

[(view `deno` preset source)](./src/presets/deno.ts)

### Built-in Node.js modules

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

| Module                                                                      | Status     | Source                                                             |
| --------------------------------------------------------------------------- | ---------- | ------------------------------------------------------------------ |
| [node:assert](https://nodejs.org/api/assert.html)                           | Mocked     | -                                                                  |
| [node:async_hooks](https://nodejs.org/api/async_hooks.html)                 | Polyfilled | [unenv/node/async_hooks](./src/runtime/node/async_hooks)           |
| [node:buffer](https://nodejs.org/api/buffer.html)                           | Polyfilled | [unenv/node/buffer](./src/runtime/node/buffer)                     |
| [node:child_process](https://nodejs.org/api/child_process.html)             | Mocked     | -                                                                  |
| [node:cluster](https://nodejs.org/api/cluster.html)                         | Mocked     | -                                                                  |
| [node:console](https://nodejs.org/api/console.html)                         | Mocked     | -                                                                  |
| [node:constants](https://nodejs.org/api/constants.html)                     | Mocked     | -                                                                  |
| [node:crypto](https://nodejs.org/api/crypto.html)                           | Polyfilled | [unenv/node/crypto](./src/runtime/node/crypto)                     |
| [node:dgram](https://nodejs.org/api/dgram.html)                             | Mocked     | -                                                                  |
| [node:diagnostics_channel](https://nodejs.org/api/diagnostics_channel.html) | Mocked     | -                                                                  |
| [node:dns](https://nodejs.org/api/dns.html)                                 | Mocked     | -                                                                  |
| [node:domain](https://nodejs.org/api/domain.html)                           | Mocked     | -                                                                  |
| [node:events](https://nodejs.org/api/events.html)                           | Polyfilled | [unenv/node/events](./src/runtime/node/events)                     |
| [node:fs](https://nodejs.org/api/fs.html)                                   | Polyfilled | [unenv/node/fs](./src/runtime/node/fs)                             |
| [node:fs/promises](https://nodejs.org/api/fs/promises.html)                 | Polyfilled | [unenv/node/fs/promises](./src/runtime/node/fs/promises)           |
| [node:http2](https://nodejs.org/api/http2.html)                             | Mocked     | -                                                                  |
| [node:http](https://nodejs.org/api/http.html)                               | Polyfilled | [unenv/node/http](./src/runtime/node/http)                         |
| [node:https](https://nodejs.org/api/https.html)                             | Polyfilled | [unenv/node/https](./src/runtime/node/https)                       |
| [node:inspector](https://nodejs.org/api/inspector.html)                     | Mocked     | -                                                                  |
| [node:module](https://nodejs.org/api/module.html)                           | Polyfilled | [unenv/node/module](./src/runtime/node/module) -                   |
| [node:net](https://nodejs.org/api/net.html)                                 | Polyfilled | [unenv/node/net](./src/runtime/node/net)                           |
| [node:os](https://nodejs.org/api/os.html)                                   | Mocked     | -                                                                  |
| [node:path](https://nodejs.org/api/path.html)                               | Polyfilled | [unenv/node/path](./src/runtime/node/path)                         |
| [node:perf_hooks](https://nodejs.org/api/perf_hooks.html)                   | Mocked     | -                                                                  |
| [node:process](https://nodejs.org/api/process.html)                         | Polyfilled | [unenv/node/process](./src/runtime/node/process)                   |
| [node:punycode](https://nodejs.org/api/punycode.html)                       | Mocked     | -                                                                  |
| [node:querystring](https://nodejs.org/api/querystring.html)                 | Mocked     | -                                                                  |
| [node:readline](https://nodejs.org/api/readline.html)                       | Mocked     | -                                                                  |
| [node:repl](https://nodejs.org/api/repl.html)                               | Mocked     | -                                                                  |
| [node:stream](https://nodejs.org/api/stream.html)                           | Polyfilled | [unenv/node/stream](./src/runtime/node/stream)                     |
| [node:stream/consumers](https://nodejs.org/api/stream.html)                 | Mocked     | [unenv/node/stream/consumers](./src/runtime/node/stream/consumers) |
| [node:stream/promises](https://nodejs.org/api/stream.html)                  | Mocked     | [unenv/node/stream/promises](./src/runtime/node/stream/promises)   |
| [node:stream/web](https://nodejs.org/api/stream.html)                       | Native     | [unenv/node/stream/web](./src/runtime/node/stream/web)             |
| [node:string_decoder](https://nodejs.org/api/string_decoder.html)           | Polyfilled | [unenv/node/string_decoder](./src/runtime/node/string_decoder)     |
| [node:sys](https://nodejs.org/api/sys.html)                                 | Mocked     | -                                                                  |
| [node:timers](https://nodejs.org/api/timers.html)                           | Mocked     | -                                                                  |
| [node:timers/promises](https://nodejs.org/api/timers.html)                  | Mocked     | -                                                                  |
| [node:tls](https://nodejs.org/api/tls.html)                                 | Mocked     | -                                                                  |
| [node:trace_events](https://nodejs.org/api/trace_events.html)               | Mocked     | -                                                                  |
| [node:tty](https://nodejs.org/api/tty.html)                                 | Mocked     | -                                                                  |
| [node:url](https://nodejs.org/api/url.html)                                 | Polyfilled | [unenv/node/url](./src/runtime/node/url)                           |
| [node:util](https://nodejs.org/api/util.html)                               | Polyfilled | [unenv/node/util](./src/runtime/node/util)                         |
| [node:util/types](https://nodejs.org/api/util.html)                         | Polyfilled | [unenv/node/util/types](./src/runtime/node/util/types)             |
| [node:v8](https://nodejs.org/api/v8.html)                                   | Mocked     | -                                                                  |
| [node:vm](https://nodejs.org/api/vm.html)                                   | Mocked     | -                                                                  |
| [node:wasi](https://nodejs.org/api/wasi.html)                               | Mocked     | -                                                                  |
| [node:worker_threads](https://nodejs.org/api/worker_threads.html)           | Mocked     | -                                                                  |
| [node:zlib](https://nodejs.org/api/zlib.html)                               | Mocked     | -                                                                  |

## npm packages

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

| Package                                                     | Status                      | Source                                                            |
| ----------------------------------------------------------- | --------------------------- | ----------------------------------------------------------------- |
| [npm/consola](https://www.npmjs.com/package/consola)        | Use native `console`        | [unenv/runtime/npm/consola](./src/runtime/npm/consola.ts)         |
| [npm/cross-fetch](https://www.npmjs.com/package/node-fetch) | Use native `fetch`          | [unenv/runtime/npm/cross-fetch](./src/runtime/npm/cross-fetch.ts) |
| [npm/debug](https://www.npmjs.com/package/debug)            | Mocked with `console.debug` | [unenv/runtime/npm/debug](./src/runtime/npm/debug.ts)             |
| [npm/fsevents](https://www.npmjs.com/package/fsevents)      | Mocked                      | [unenv/runtime/npm/fsevents](./src/runtime/npm/fsevents.ts)       |
| [npm/inherits](https://www.npmjs.com/package/inherits)      | Inlined                     | [unenv/runtime/npm/inherits](./src/runtime/npm/inherits.ts)       |
| [npm/mime-db](https://www.npmjs.com/package/mime-db)        | Minimized                   | [unenv/runtime/npm/mime-db](./src/runtime/npm/mime-db.ts)         |
| [npm/mime](https://www.npmjs.com/package/mime)              | Minimized                   | [unenv/runtime/npm/mime](./src/runtime/npm/mime.ts)               |
| [npm/node-fetch](https://www.npmjs.com/package/node-fetch)  | Use native `fetch`          | [unenv/runtime/npm/node-fetch](./src/runtime/npm/node-fetch.ts)   |
| [npm/whatwg-url](https://www.npmjs.com/package/whatwg-url)  | Use native `URL`            | [unenv/runtime/npm/whatwg-url](./src/runtime/npm/whatwg-url.ts)   |

## Auto-mocking proxy

```js
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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) 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:

```js
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](./src/runtime).

## License

MIT