Configuring Vite

Config File

Config File Resolving

When running vite from the command line, Vite will automatically try to resolve a config file named vite.config.js inside project root.

The most basic config file looks like this:

// vite.config.js
export default {
  // config options
}

Note Vite supports using ES modules syntax in the config file even if the project is not using native Node ESM via type: "module". In this case, the config file is auto pre-processed before load.

You can also explicitly specify a config file to use with the --config CLI option (resolved relative to cwd):

vite --config my-config.js

Config Intellisense

Since Vite ships with TypeScript typings, you can leverage your IDE's intellisense with jsdoc type hints:

/**
 * @type {import('vite').UserConfig}
 */
const config = {
  // ...
}

export default config

Alternatively, you can use the defineConfig helper which should provide intellisense without the need for jsdoc annotations:

import { defineConfig } from 'vite'

export default defineConfig({
  // ...
})

Vite also directly supports TS config files. You can use vite.config.ts with the defineConfig helper as well.

Conditional Config

If the config needs to conditional determine options based on the command (serve or build) or the mode being used, it can export a function instead:

export default ({ command, mode }) => {
  if (command === 'serve') {
    return {
      // serve specific config
    }
  } else {
    return {
      // build specific config
    }
  }
}

Async Config

If the config needs to call async function, it can export a async function instead:

export default async ({ command, mode }) => {
  const data = await asyncFunction()
  return {
    // build specific config
  }
}

Shared Options

root

Type: string
Default: process.cwd()

Project root directory (where index.html is located). Can be an absolute path, or a path relative to the location of the config file itself.

See Project Root for more details.

base

Type: string
Default: /

Base public path when served in development or production. Valid values include:
- Absolute URL pathname, e.g. /foo/
- Full URL, e.g. https://foo.com/
- Empty string or ./ (for embedded deployment)
See Public Base Path for more details.

mode

Type: string
Default: 'development' for serve, 'production' for build

Specifying this in config will override the default mode for both serve and build. This value can also be overridden via the command line --mode option.

See Env Variables and Modes for more details.

define

Type: Record<string, string>

Define global constant replacements. Entries will be defined as globals during dev and statically replaced during build.
- Starting from 2.0.0-beta.70, string values will be used as raw expressions, so if defining a string constant, it needs to be explicitly quoted (e.g. with JSON.stringify).
- Replacements are performed only when the match is surrounded by word boundaries (\b).
Because it's implemented as straightforward text replacements without any syntax analysis, we recommend using define for CONSTANTS only.

For example, process.env.FOO and __APP_VERSION__ are good fits. But process or global should not be put into this option. Variables can be shimmed or polyfilled instead.

plugins

Type: (Plugin | Plugin[])[]

Array of plugins to use. Falsy plugins are ignored and arrays of plugins are flattened. See Plugin API for more details on Vite plugins.

publicDir

Type: string
Default: "public"

Directory to serve as plain static assets. Files in this directory are served at / during dev and copied to the root of outDir during build, and are always served or copied as-is without transform. The value can be either an absolute file system path or a path relative to project root.

See The public Directory for more details.

cacheDir

Type: string
Default: "node_modules/.vite"

Directory to save cache files. Files in this directory are pre-bundled deps or some other cache files generated by vite, which can improve the performance. You can use --force flag or manually delete the directory to regenerate the cache files. The value can be either an absolute file system path or a path relative to project root.

resolve.alias

Type: Record<string, string> | Array<{ find: string | RegExp, replacement: string }>

Will be passed to @rollup/plugin-alias as its entries option. Can either be an object, or an array of { find, replacement } pairs.

When aliasing to file system paths, always use absolute paths. Relative alias values will be used as-is and will not be resolved into file system paths.

More advanced custom resolution can be achieved through plugins.

resolve.dedupe

Type: string[]

If you have duplicated copies of the same dependency in your app (likely due to hoisting or linked packages in monorepos), use this option to force Vite to always resolve listed dependencies to the same copy (from project root).

resolve.conditions

Type: string[]

Additional allowed conditions when resolving Conditional Exports from a package.

A package with conditional exports may have the following exports field in its package.json:
```
{
  "exports": {
    ".": {
      "import": "./index.esm.js",
      "require": "./index.cjs.js"
    }
  }
}
```
Here, import and require are "conditions". Conditions can be nested and should be specified from most specific to least specific.

Vite has a list of "allowed conditions" and will match the first condition that is in the allowed list. The default allowed conditions are: import, module, browser, default, and production/development based on current mode. The resolve.conditions config option allows specifying additional allowed conditions.

resolve.mainFields

Type: string[]
Default: ['module', 'jsnext:main', 'jsnext']

List of fields in package.json to try when resolving a package's entry point. Note this takes lower precedence than conditional exports resolved from the exports field: if an entry point is successfully resolved from exports, the main field will be ignored.

resolve.extensions

Type: string[]
Default: ['.mjs', '.js', '.ts', '.jsx', '.tsx', '.json']

List of file extensions to try for imports that omit extensions. Note it is NOT recommended to omit extensions for custom import types (e.g. .vue) since it can interfere with IDE and type support.

css.modules

Type:

interface CSSModulesOptions {
  scopeBehaviour?: 'global' | 'local'
  globalModulePaths?: string[]
  generateScopedName?:
    | string
    | ((name: string, filename: string, css: string) => string)
  hashPrefix?: string
  /**
   * default: 'camelCaseOnly'
   */
  localsConvention?: 'camelCase' | 'camelCaseOnly' | 'dashes' | 'dashesOnly'
}

Configure CSS modules behavior. The options are passed on to postcss-modules.

css.postcss

Type: string | (postcss.ProcessOptions & { plugins?: postcss.Plugin[] })

Inline PostCSS config (expects the same format as postcss.config.js), or a custom path to search PostCSS config from (default is project root). The search is done using postcss-load-config.

Note if an inline config is provided, Vite will not search for other PostCSS config sources.

css.preprocessorOptions

Type: Record<string, object>

Specify options to pass to CSS pre-processors. Example:

export default {
  css: {
    preprocessorOptions: {
      scss: {
        additionalData: `$injectedColor: orange;`
      }
    }
  }
}

json.namedExports

Type: boolean
Default: true

Whether to support named imports from .json files.

json.stringify

Type: boolean
Default: false

If set to true, imported JSON will be transformed into export default JSON.parse("...") which is significantly more performant than Object literals, especially when the JSON file is large.

Enabling this disables named imports.

esbuild

Type: ESBuildOptions | false

ESBuildOptions extends ESbuild's own transform options. The most common use case is customizing JSX:
```
export default {
  esbuild: {
    jsxFactory: 'h',
    jsxFragment: 'Fragment'
  }
}
```
By default, ESBuild is applied to ts, jsx and tsx files. You can customize this with esbuild.include and esbuild.exclude, both of which expect type of string | RegExp | (string | RegExp)[].

In addition, you can also use esbuild.jsxInject to automatically inject JSX helper imports for every file transformed by ESBuild:
```
export default {
  esbuild: {
    jsxInject: `import React from 'react'`
  }
}
```
Set to false to disable ESbuild transforms.

assetsInclude

Type: string | RegExp | (string | RegExp)[]
Related: Static Asset Handling

Specify additional file types to be treated as static assets so that:
- They will be excluded from the plugin transform pipeline when referenced from HTML or directly requested over fetch or XHR.
- Importing them from JS will return their resolved URL string (this can be overwritten if you have a enforce: 'pre' plugin to handle the asset type differently).
The built-in asset type list can be found here.

logLevel

Type: 'info' | 'warn' | 'error' | 'silent'

Adjust console output verbosity. Default is 'info'.

clearScreen

Type: boolean
Default: true

Set to false to prevent Vite from clearing the terminal screen when logging certain messages. Via command line, use --clearScreen false.

envDir

Type: string
Default: root

The directory from which .env files are loaded. Can be an absolute path, or a path relative to the project root.

See here for more about environment files.

Server Options

server.host

Type: string
Default: '127.0.0.1'

Specify which IP addresses the server should listen on. Set this to 0.0.0.0 to listen on all addresses, including LAN and public addresses.

This can be set via the CLI using --host 0.0.0.0 or --host.

server.port

Type: number

Specify server port. Note if the port is already being used, Vite will automatically try the next available port so this may not be the actual port the server ends up listening on.

server.strictPort

Type: boolean

Set to true to exit if port is already in use, instead of automatically try the next available port.

server.https

Type: boolean | https.ServerOptions

Enable TLS + HTTP/2. Note this downgrades to TLS only when the server.proxy option is also used.

The value can also be an options object passed to https.createServer().

server.open

Type: boolean | string

Automatically open the app in the browser on server start. When the value is a string, it will be used as the URL's pathname. If you want to open the server in a specific browser you like, you can set the env process.env.BROWSER (e.g. firefox). See the open package for more details.

Example:
```
export default {
  server: {
    open: '/docs/index.html'
  }
}
```

server.proxy

Type: Record<string, string | ProxyOptions>

Configure custom proxy rules for the dev server. Expects an object of { key: options } pairs. If the key starts with ^, it will be interpreted as a RegExp. The configure option can be used to access the proxy instance.

Uses http-proxy. Full options here.

Example:

export default {
  server: {
    proxy: {
      // string shorthand
      '/foo': 'http://localhost:4567/foo',
      // with options
      '/api': {
        target: 'http://jsonplaceholder.typicode.com',
        changeOrigin: true,
        rewrite: (path) => path.replace(/^\/api/, '')
      },
      // with RegEx
      '^/fallback/.*': {
        target: 'http://jsonplaceholder.typicode.com',
        changeOrigin: true,
        rewrite: (path) => path.replace(/^\/fallback/, '')
      },
      // Using the proxy instance
      '/api': {
        target: 'http://jsonplaceholder.typicode.com',
        changeOrigin: true,
        configure: (proxy, options) => {
          // proxy will be an instance of 'http-proxy'
        }),
      }
    }
  }
}

server.cors

Type: boolean | CorsOptions

Configure CORS for the dev server. This is enabled by default and allows any origin. Pass an options object to fine tune the behavior or false to disable.

server.force

Type: boolean
Related: Dependency Pre-Bundling

Set to true to force dependency pre-bundling.

server.hmr

Type: boolean | { protocol?: string, host?: string, port?: number, path?: string, timeout?: number, overlay?: boolean, clientPort?: number, server?: Server }

Disable or configure HMR connection (in cases where the HMR websocket must use a different address from the http server).

Set server.hmr.overlay to false to disable the server error overlay.

clientPort is an advanced option that overrides the port only on the client side, allowing you to serve the websocket on a different port than the client code looks for it on. Useful if you're using an SSL proxy in front of your dev server.

When using server.middlewareMode and server.https, setting server.hmr.server to your HTTPS server will process HMR secure connection requests through your server. This can be helpful when using self-signed certificates.

server.watch

Type: object

File system watcher options to pass on to chokidar.

server.middlewareMode

Type: 'ssr' | 'html'

Create Vite server in middleware mode. (without a HTTP server)
- 'ssr' will disable Vite's own HTML serving logic so that you should serve index.html manually.
- 'html' will enable Vite's own HTML serving logic.
Related: SSR - Setting Up the Dev Server
Example:

const express = require('express')
const { createServer: createViteServer } = require('vite')

async function createServer() {
  const app = express()

  // Create vite server in middleware mode.
  const vite = await createViteServer({
    server: { middlewareMode: 'ssr' }
  })
  // Use vite's connect instance as middleware
  app.use(vite.middlewares)

  app.use('*', async (req, res) => {
    // If `middlewareMode` is `'ssr'`, should serve `index.html` here.
    // If `middlewareMode` is `'html'`, there is no need to serve `index.html`
    // because Vite will do that.
  })
}

createServer()

server.fs.strict

Experimental
Type: boolean
Default: false (will change to true in future versions)

Restrict serving files outside of workspace root.

server.fs.allow

Experimental
Type: string[]

Restrict files that could be served via /@fs/. When server.fs.strict is set to true, accessing files outside this directory list will result in a 403.

Vite will search for the root of the potential workspace and use it as default. A valid workspace met the following conditions, otherwise will fallback to the project root.
- contains workspaces field in package.json
- contains one of the following file
  - pnpm-workspace.yaml
Accepts a path to specify the custom workspace root. Could be a absolute path or a path relative to project root. For example
```
export default {
  server: {
    fs: {
      // Allow serving files from one level up to the project root
      allow: [
        '..'
      ]
    }
  }
}
```

Build Options

build.target

Type: string
Default: 'modules'
Related: Browser Compatibility

Browser compatibility target for the final bundle. The default value is a Vite special value, 'modules', which targets browsers with native ES module support.

Another special value is 'esnext' - which assumes native dynamic imports support and will transpile as little as possible:
- If the build.minify option is 'terser' (the default), 'esnext' will be forced down to 'es2019'.
- In other cases, it will perform no transpilation at all.
The transform is performed with esbuild and the value should be a valid esbuild target option. Custom targets can either be a ES version (e.g. es2015), a browser with version (e.g. chrome58), or an array of multiple target strings.

Note the build will fail if the code contains features that cannot be safely transpiled by esbuild. See esbuild docs for more details.

build.polyfillDynamicImport

Type: boolean
Default: false

Whether to automatically inject dynamic import polyfill.

If set to true, the polyfill is auto injected into the proxy module of each index.html entry. If the build is configured to use a non-html custom entry via build.rollupOptions.input, then it is necessary to manually import the polyfill in your custom entry:
```
import 'vite/dynamic-import-polyfill'
```
When using @vitejs/plugin-legacy, the plugin sets this option to true automatically.

Note: the polyfill does not apply to Library Mode. If you need to support browsers without native dynamic import, you should probably avoid using it in your library.

build.outDir

Type: string
Default: dist

Specify the output directory (relative to project root).

build.assetsDir

Type: string
Default: assets

Specify the directory to nest generated assets under (relative to build.outDir).

build.assetsInlineLimit

Type: number
Default: 4096 (4kb)

Imported or referenced assets that are smaller than this threshold will be inlined as base64 URLs to avoid extra http requests. Set to 0 to disable inlining altogether.

::: tip Note If you specify build.lib, build.assetsInlineLimit will be ignored and assets will always be inlined, regardless of file size. :::

build.cssCodeSplit

Type: boolean
Default: true

Enable/disable CSS code splitting. When enabled, CSS imported in async chunks will be inlined into the async chunk itself and inserted when the chunk is loaded.

If disabled, all CSS in the entire project will be extracted into a single CSS file.

build.sourcemap

Type: boolean | 'inline' | 'hidden'
Default: false

Generate production source maps.

build.rollupOptions

Type: RollupOptions

Directly customize the underlying Rollup bundle. This is the same as options that can be exported from a Rollup config file and will be merged with Vite's internal Rollup options. See Rollup options docs for more details.

build.commonjsOptions

Type: RollupCommonJSOptions

Options to pass on to @rollup/plugin-commonjs.

build.dynamicImportVarsOptions

Type: RollupDynamicImportVarsOptions

Options to pass on to @rollup/plugin-dynamic-import-vars.

build.lib

Type: { entry: string, name?: string, formats?: ('es' | 'cjs' | 'umd' | 'iife')[], fileName?: string }
Related: Library Mode

Build as a library. entry is required since the library cannot use HTML as entry. name is the exposed global variable and is required when formats includes 'umd' or 'iife'. Default formats are ['es', 'umd']. fileName is the name of the package file output, default fileName is the name option of package.json

build.manifest

Type: boolean
Default: false
Related: Backend Integration

When set to true, the build will also generate a manifest.json file that contains a mapping of non-hashed asset filenames to their hashed versions, which can then be used by a server framework to render the correct asset links.

build.minify

Type: boolean | 'terser' | 'esbuild'
Default: 'terser'

Set to false to disable minification, or specify the minifier to use. The default is Terser which is slower but produces smaller bundles in most cases. Esbuild minification is significantly faster but will result in slightly larger bundles.

build.terserOptions

Type: TerserOptions

Additional minify options to pass on to Terser.

build.cleanCssOptions

Type: CleanCSS.Options

Constructor options to pass on to clean-css.

build.write

Type: boolean
Default: true

Set to false to disable writing the bundle to disk. This is mostly used in programmatic build() calls where further post processing of the bundle is needed before writing to disk.

build.emptyOutDir

Type: boolean
Default: true if outDir is inside root

By default, Vite will empty the outDir on build if it is inside project root. It will emit a warning if outDir is outside of root to avoid accidentially removing important files. You can explicitly set this option to suppress the warning. This is also available via command line as --emptyOutDir.

build.brotliSize

Type: boolean
Default: true

Enable/disable brotli-compressed size reporting. Compressing large output files can be slow, so disabling this may increase build performance for large projects.

build.chunkSizeWarningLimit

Type: number
Default: 500

Limit for chunk size warnings (in kbs).

build.watch

Type: WatcherOptions| null
Default: null

Set to {} to enable rollup watcher. This is mostly used in cases that involve build-only plugins or integrations processes.

Dep Optimization Options

Related: Dependency Pre-Bundling

optimizeDeps.entries

Type: string | string[]

By default, Vite will crawl your index.html to detect dependencies that need to be pre-bundled. If build.rollupOptions.input is specified, Vite will crawl those entry points instead.

If neither of these fit your needs, you can specify custom entries using this option - the value should be a fast-glob pattern or array of patterns that are relative from vite project root. This will overwrite default entries inference.

optimizeDeps.exclude

Type: string[]

Dependencies to exclude from pre-bundling.

:::warning CommonJS CommonJS dependencies should not be excluded from optimization. If an ESM dependency has a nested CommonJS dependency, it should not be excluded as well. :::

optimizeDeps.include

Type: string[]

By default, linked packages not inside node_modules are not pre-bundled. Use this option to force a linked package to be pre-bundled.

optimizeDeps.keepNames

Type: boolean
Default: false

The bundler sometimes needs to rename symbols to avoid collisions. Set this to true to keep the name property on functions and classes. See keepNames.

SSR Options

:::warning Experimental SSR options may be adjusted in minor releases. :::

Related: SSR Externals

ssr.external

Type: string[]

Force externalize dependencies for SSR.

ssr.noExternal

Type: string | RegExp | (string | RegExp)[]

Prevent listed dependencies from being externalized for SSR.

ssr.target

Type: 'node' | 'webworker'
Default: node

Build target for the SSR server.

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