@vitejs/plugin-react-swc/README.md

Speed up your Vite dev server with SWC

# @vitejs/plugin-react-swc [![npm](https://img.shields.io/npm/v/@vitejs/plugin-react-swc)](https://www.npmjs.com/package/@vitejs/plugin-react-swc)

Speed up your Vite dev server with [SWC](https://swc.rs/)

- ✅ A fast Fast Refresh (~20x faster than Babel)
- ✅ Enable [automatic JSX runtime](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html)

## Installation

```sh
npm i -D @vitejs/plugin-react-swc
```

## Usage

```ts
import { defineConfig } from 'vite'
import react from '@vitejs/plugin-react-swc'

export default defineConfig({
  plugins: [react()],
})
```

## Caveats

This plugin has limited options to enable good performances and be transpiler agnostic. Here is the list of non-configurable options that impact runtime behaviour:

- [useDefineForClassFields](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#the-usedefineforclassfields-flag-and-the-declare-property-modifier) is always activated, as this matches the current ECMAScript spec
- `jsx runtime` is always `automatic`
- In development:
  - esbuild is disabled, so the [esbuild configuration](https://vite.dev/config/shared-options.html#esbuild) has no effect
  - `target` is ignored and defaults to `es2020` (see [`devTarget`](#devtarget))
  - JS files are not transformed
  - tsconfig is not resolved, so properties other than the ones listed above behaves like TS defaults

## Options

### jsxImportSource

Control where the JSX factory is imported from.

`@default` "react"

```ts
react({ jsxImportSource: '@emotion/react' })
```

### tsDecorators

Enable TypeScript decorators. Requires `experimentalDecorators` in tsconfig.

`@default` false

```ts
react({ tsDecorators: true })
```

### plugins

Use SWC plugins. Enable SWC at build time.

```ts
react({ plugins: [['@swc/plugin-styled-components', {}]] })
```

### devTarget

Set the target for SWC in dev. This can avoid to down-transpile private class method for example.

For production target, see https://vite.dev/config/build-options.html#build-target.

`@default` "es2020"

```ts
react({ devTarget: 'es2022' })
```

### parserConfig

Override the default include list (.ts, .tsx, .mts, .jsx, .mdx).

This requires to redefine the config for any file you want to be included (ts, mdx, ...).

If you want to trigger fast refresh on compiled JS, use `jsx: true`. Exclusion of node_modules should be handled by the function if needed. Using this option to use JSX inside `.js` files is highly discouraged and can be removed in any future version.

```ts
react({
  parserConfig(id) {
    if (id.endsWith('.res')) return { syntax: 'ecmascript', jsx: true }
    if (id.endsWith('.ts')) return { syntax: 'typescript', tsx: false }
  },
})
```

### reactRefreshHost

The `reactRefreshHost` option is only necessary in a module federation context. It enables HMR to work between a remote & host application. In your remote Vite config, you would add your host origin:

```js
react({ reactRefreshHost: 'http://localhost:3000' })
```

Under the hood, this simply updates the React Fash Refresh runtime URL from `/@react-refresh` to `http://localhost:3000/@react-refresh` to ensure there is only one Refresh runtime across the whole application. Note that if you define `base` option in the host application, you need to include it in the option, like: `http://localhost:3000/{base}`.

### useAtYourOwnRisk_mutateSwcOptions

The future of Vite is with OXC, and from the beginning this was a design choice to not exposed too many specialties from SWC so that Vite React users can move to another transformer later.
Also debugging why some specific version of decorators with some other unstable/legacy feature doesn't work is not fun, so we won't provide support for it, hence the name `useAtYourOwnRisk`.

```ts
react({
  useAtYourOwnRisk_mutateSwcOptions(options) {
    options.jsc.parser.decorators = true
    options.jsc.transform.decoratorVersion = '2022-03'
  },
})
```

## Consistent components exports

For React refresh to work correctly, your file should only export React components. The best explanation I've read is the one from the [Gatsby docs](https://www.gatsbyjs.com/docs/reference/local-development/fast-refresh/#how-it-works).

If an incompatible change in exports is found, the module will be invalidated and HMR will propagate. To make it easier to export simple constants alongside your component, the module is only invalidated when their value changes.

You can catch mistakes and get more detailed warning with this [eslint rule](https://github.com/ArnaudBarre/eslint-plugin-react-refresh).