Config Options

🚧 Under Construction

We are working on generating a more detailed reference. For now, please refer to Rollup's Config Options Reference and documentation on additional notable features.

InputOptions

input

plugins

external

resolve

resolve.alias

WARNING

resolve.alias will not call resolveId hooks of other plugin. If you want to call resolveId hooks of other plugin, use aliasPlugin from rolldown/experimental instead. You could find more discussion in this issue

resolve.aliasFields

resolve.conditionNames

resolve.extensionAlias

Map of extensions to alternative extensions.

With writing import './foo.js' in a file, you want to resolve it to foo.ts instead of foo.js. You can achieve this by setting: extensionAlias: { '.js': ['.ts', '.js'] }.

resolve.exportsFields

resolve.extensions

resolve.mainFields

resolve.mainFiles

resolve.modules

resolve.symlinks

resolve.tsconfigFilename

cwd

platform

Expected platform where the code run.

When the platform is set to neutral:

• When bundling is enabled the default output format is set to esm, which uses the export syntax introduced with ECMAScript 2015 (i.e. ES6). You can change the output format if this default is not appropriate.
• The main fields setting is empty by default. If you want to use npm-style packages, you will likely have to configure this to be something else such as main for the standard main field used by node.
• The conditions setting does not automatically include any platform-specific values.

shimMissingExports

treeshake

logLevel

onLog

onwarn

moduleTypes

experimental

experimental.strictExecutionOrder

experimental.disableLiveBindings

experimental.viteMode

experimental.resolveNewUrlToAsset

experimental.hmr

experimental.chunkModulesOrder

Control which order should use when rendering modules in chunk

• Type: `'exec-order' | 'module-id'

• Default: 'exec-order'

• exec-order: Almost equivalent to the topological order of the module graph, but specially handling when module graph has cycle.

• module-id: This is more friendly for gzip compression, especially for some javascript static asset lib (e.g. icon library)

NOTE

Try to sort the modules by their module id if possible(Since rolldown scope hoist all modules in the chunk, we only try to sort those modules by module id if we could ensure runtime behavior is correct after sorting).

experimental.attachDebugInfo

experimental.chunkImportMap

Enables automatic generation of a chunk import map asset during build.

This map only includes chunks with hashed filenames, where keys are derived from the facade module name or primary chunk name. It produces stable and unique hash-based filenames, effectively preventing cascading cache invalidation caused by content hashes and maximizing browser cache reuse.

The output defaults to importmap.json unless overridden via fileName. A base URL prefix (default "/") can be applied to all paths. The resulting JSON is a valid import map and can be directly injected into HTML via <script type="importmap">.

Example configuration snippet:

{
  experimental: {
    chunkImportMap: {
      baseUrl: '/',
      fileName: 'importmap.json'
    }
  },
  plugins: [
    {
      name: 'inject-import-map',
      generateBundle(_, bundle) {
        const chunkImportMap = bundle['importmap.json'];
        if (chunkImportMap?.type === 'asset') {
          const htmlPath = path.resolve('index.html');
          let html = fs.readFileSync(htmlPath, 'utf-8');

          html = html.replace(
            /<script\s+type="importmap"[^>]*>[\s\S]*?</script>/i,
            `<script type="importmap">${chunkImportMap.source}</script>`
          );

          fs.writeFileSync(htmlPath, html);
          delete bundle['importmap.json'];
        }
      }
    }
  ]
}

NOTE

If you want to learn more, you can check out the example here: examples/chunk-import-map

experimental.onDemandWrapping

experimental.incrementalBuild

Required to be used with watch mode.

experimental.transformHiresSourcemap

define

Replace global variables or property accessors with the provided values.

Examples

• Replace the global variable IS_PROD with true

export default defineConfig({ define: { IS_PROD: 'true' // or JSON.stringify(true) } })

Result:

// Input
if (IS_PROD) {
  console.log('Production mode')
}

// After bundling
if (true) {
  console.log('Production mode')
}

• Replace the property accessor process.env.NODE_ENV with 'production'

export default defineConfig({ define: { 'process.env.NODE_ENV': "'production'" } })

Result:

// Input
if (process.env.NODE_ENV === 'production') {
 console.log('Production mode')
}

// After bundling
if ('production' === 'production') {
console.log('Production mode')
}

inject

Inject import statements on demand.

Supported patterns

{
  // import { Promise } from 'es6-promise'
  Promise: ['es6-promise', 'Promise'],

  // import { Promise as P } from 'es6-promise'
  P: ['es6-promise', 'Promise'],

  // import $ from 'jquery'
  $: 'jquery',

  // import * as fs from 'node:fs'
  fs: ['node:fs', '*'],

  // Inject shims for property access pattern
  'Object.assign': path.resolve( 'src/helpers/object-assign.js' ),
}

profilerNames

jsx

transform

Configure how the code is transformed. This process happens after the transform hook.

To transpile legacy decorators, you could use

export default defineConfig({
  transform: {
    decorator: {
      legacy: true,
    },
  },
})

For latest decorators proposal, rolldown is able to bundle them but doesn't support transpiling them yet.

watch

dropLabels

keepNames

checks

makeAbsoluteExternalsRelative

debug

debug.sessionId

preserveEntrySignatures

optimization

optimization.inlineConst

Inline imported constant values during bundling instead of preserving variable references.

When enabled, constant values from imported modules will be inlined at their usage sites, potentially reducing bundle size and improving runtime performance by eliminating variable lookups. options:

• true: equivalent to { mode: 'all', pass: 1 }, enabling constant inlining for all eligible constants with a single pass.
• false: Disable constant inlining
• { mode: 'smart' | 'all', pass?: number }:
  • mode: 'smart': Only inline constants in specific scenarios where it is likely to reduce bundle size and improve performance. Smart mode inlines constants in these specific scenarios:
    1. if (test) {} else {} - condition expressions in if statements
    2. test ? a : b - condition expressions in ternary operators
    3. test1 || test2 - logical OR expressions
    4. test1 && test2 - logical AND expressions
    5. test1 ?? test2 - nullish coalescing expressions
• mode: 'all': Inline all imported constants wherever they are used.
• pass: Number of passes to perform for inlining constants.

example

// Input files:
// constants.js
export const API_URL = 'https://api.example.com';

// main.js
import { API_URL } from './constants.js';
console.log(API_URL);

// With inlineConst: true, the bundled output becomes:
console.log('https://api.example.com');

// Instead of:
const API_URL = 'https://api.example.com';
console.log(API_URL);

context

tsconfig

Allows you to specify where to find the TypeScript configuration file.

You may provide:

• a relative path to the configuration file. It will be resolved relative to cwd.
• an absolute path to the configuration file.

When a tsconfig path is specified, the module resolver will respect compilerOptions.paths from the specified tsconfig.json, and the tsconfig options will be merged with the top-level transform options, with the transform options taking precedence.

OutputOptions

dir

file

exports

hashCharacters

format

sourcemap

sourcemapBaseUrl

sourcemapDebugIds

sourcemapIgnoreList

sourcemapPathTransform

banner

footer

intro

outro

extend

esModule

assetFileNames

entryFileNames

chunkFileNames

cssEntryFileNames

cssChunkFileNames

sanitizeFileName

minify

Control code minification.

• true: Enable full minification including code compression and dead code elimination
• false: Disable minification (default)
• 'dce-only': Only perform dead code elimination without code compression
• MinifyOptions: Fine-grained control over minification settings

name

globals

externalLiveBindings

inlineDynamicImports

manualChunks

• Type: ((moduleId: string, meta: { getModuleInfo: (moduleId: string) => ModuleInfo | null }) => string | NullValue)
• Object form is not supported.

WARNING

• This option is deprecated. Please use advancedChunks instead.
• If manualChunks and advancedChunks are both specified, manualChunks option will be ignored.

You could use this option for migration purpose. Under the hood,

{
  manualChunks: (moduleId, meta) => {
    if (moduleId.includes('node_modules')) {
      return 'vendor';
    }
    return null;
  }
}

will be transformed to

{
  advancedChunks: {
    groups: [
      {
        name(moduleId) {
          if (moduleId.includes('node_modules')) {
            return 'vendor';
          }
          return null;
        },
      },
    ],
  }
}

advancedChunks

Allows you to do manual chunking. For deeper understanding, please refer to the in-depth documentation.

advancedChunks.includeDependenciesRecursively

• Type: boolean
• Default: true

By default, each group will also include captured modules' dependencies. This reduces the chance of generating circular chunks.

If you want to disable this behavior, it's recommended to both set

• preserveEntrySignatures: false
• strictExecutionOrder: true

to avoid generating invalid chunks.

advancedChunks.minSize

• Type: number

Global fallback of {group}.minSize, if it's not specified in the group.

advancedChunks.maxSize

• Type: number

Global fallback of {group}.maxSize, if it's not specified in the group.

advancedChunks.maxModuleSize

• Type: number

Global fallback of {group}.maxModuleSize, if it's not specified in the group.

advancedChunks.minModuleSize

• Type: number

Global fallback of {group}.minModuleSize, if it's not specified in the group.

advancedChunks.minShareCount

• Type: number

Global fallback of {group}.minShareCount, if it's not specified in the group.

advancedChunks.groups

Groups to be used for advanced chunking.

advancedChunks.groups.name

• Type: string | ((moduleId: string, ctx: { getModuleInfo: (moduleId: string) => ModuleInfo | null }) => string | NullValue)

Name of the group. It will be also used as the name of the chunk and replaced the [name] placeholder in the chunkFileNames option.

For example,

import { defineConfig } from 'rolldown';

export default defineConfig({
  advancedChunks: {
    groups: [
      {
        name: 'libs',
        test: /node_modules/,
      },
    ],
  },
});

will create a chunk named libs-[hash].js in the end.

It's ok to have the same name for different groups. Rolldown will deduplicate the chunk names if necessary.

Dynamic name()

If name is a function, it will be called with the module id as the argument. The function should return a string or null. If it returns null, the module will be ignored by this group.

Notice, each returned new name will be treated as a separate group.

For example,

import { defineConfig } from 'rolldown';

export default defineConfig({
  advancedChunks: {
    groups: [
      {
        name: (moduleId) => moduleId.includes('node_modules') ? 'libs' : 'app',
        minSize: 100 * 1024,
      },
    ],
  },
});

WARNING

Constraints like minSize, maxSize, etc. are applied separately for different names returned by the function.

advancedChunks.groups.test

• Type: string | RegExp | ((id: string) => boolean | undefined | void);

Controls which modules are captured in this group.

• If test is a string, the module whose id contains the string will be captured.
• If test is a regular expression, the module whose id matches the regular expression will be captured.
• If test is a function, modules for which test(id) returns true will be captured.
• If test is empty, any module will be considered as matched.

WARNING

When using regular expression, it's recommended to use [\\/] to match the path separator instead of / to avoid potential issues on Windows.

• ✅ Recommended: /node_modules[\\/]react/
• ❌ Not recommended: /node_modules/react/

advancedChunks.groups.priority

• Type: number
• Default: 0

Priority of the group. Group with higher priority will be chosen first to match modules and create chunks. When converting the group to a chunk, modules of that group will be removed from other groups.

If two groups have the same priority, the group whose index is smaller will be chosen.

For example,

import { defineConfig } from 'rolldown';

export default defineConfig({
 advancedChunks: {
  groups: [
     {
       name: 'react',
       test: /node_modules[\\/]react/,
       priority: 1,
     },
     {
       name: 'other-libs',
       test: /node_modules/,
       priority: 2,
     },
  ],
});

This is a clearly incorrect example. Though react group is defined before other-libs, it has a lower priority, so the modules in react group will be captured in other-libs group.

advancedChunks.groups.minSize

• Type: number
• Default: 0

Minimum size in bytes of the desired chunk. If the accumulated size of the captured modules by this group is smaller than this value, it will be ignored. Modules in this group will fall back to the automatic chunking if they are not captured by any other group.

advancedChunks.groups.minShareCount

• Type: number
• Default: 1

Controls if a module should be captured based on how many entry chunks reference it.

advancedChunks.groups.maxSize

• Type: number
• Default: Infinity

If the accumulated size in bytes of the captured modules by this group is larger than this value, this group will be split into multiple groups that each has size close to this value.

advancedChunks.groups.maxModuleSize

• Type: number
• Default: Infinity

Controls a module could only be captured if its size in bytes is smaller or equal than this value.

advancedChunks.groups.minModuleSize

• Type: number
• Default: 0

Controls a module could only be captured if its size in bytes is larger or equal than this value.

legalComments

Control comments in the output.

• none: no comments
• inline: preserve comments that contain @license, @preserve or starts with //! /*!

plugins

polyfillRequire

hoistTransitiveImports

preserveModules

virtualDirname

preserveModulesRoot

topLevelVar

minifyInternalExports

• Type: boolean
• Default: false

Whether to minify internal exports.