output

Configuration options for the output bundle. These options control how Rolldown generates the final bundled files.

dir

Type: string
Optional: Yes ✅
Path: output.dir

The directory where output files will be written. Required when using multiple entry points.

Examples

export default {
  input: {
    main: 'src/index.js',
    admin: 'src/admin.js',
  },
  output: {
    dir: 'dist',
  },
};

file

Type: string
Optional: Yes ✅
Path: output.file

The file path for the output bundle. Used for single entry builds.

Examples

export default {
  input: 'src/index.js',
  output: {
    file: 'dist/bundle.js',
  },
};

In-depth

Use file for single-entry builds and dir for multi-entry builds.

exports

Type: 'auto' | 'named' | 'default' | 'none'
Default: 'auto'
Path: output.exports

Specifies what export mode to use for the bundle.

Examples

export default {
  output: {
    format: 'cjs',
    exports: 'named',
  },
};

In-depth

The available modes:

'auto': Automatically determines the export mode based on the entry module's exports (recommended)
'named': Exports are exposed as named exports
'default': The entry module's default export is used as the main export
'none': No exports (useful for side-effect-only bundles)

hashCharacters

Type: 'base64' | 'base36' | 'hex'
Default: 'base64'
Path: output.hashCharacters

The character set to use for content hashes in file names.

Examples

export default {
  output: {
    hashCharacters: 'hex',
    entryFileNames: '[name]-[hash].js',
  },
};

In-depth

The available character sets:

'base64': Uses base64 characters (shortest hashes)
'base36': Uses alphanumeric characters (0-9, a-z)
'hex': Uses hexadecimal characters (0-9, a-f)

format

Type: 'es' | 'cjs' | 'esm' | 'module' | 'commonjs' | 'iife' | 'umd'
Default: 'esm'
Path: output.format

Expected format of generated code.

Examples

export default {
  output: {
    format: 'esm',
  },
};

In-depth

The available formats:

'es', 'esm', 'module': ES module format (uses import and export)
'cjs', 'commonjs': CommonJS format (uses require() and module.exports)
'iife': Immediately Invoked Function Expression (requires name option)
'umd': Universal Module Definition (requires name option)

sourcemap

Type: boolean | 'inline' | 'hidden'
Default: false
Path: output.sourcemap

Controls source map generation and configuration. See output.sourcemap for detailed nested options.

Examples

export default {
  output: {
    sourcemap: true,
  },
};

Type: string | ((chunk: RenderedChunk) => string | Promise<string>)
Optional: Yes ✅
Path: output.banner

Code to prepend to the beginning of each output chunk.

Examples

export default {
  output: {
    banner: '/* My Library v1.0.0 | MIT License */',
  },
};

Type: string | ((chunk: RenderedChunk) => string | Promise<string>)
Optional: Yes ✅
Path: output.footer

Code to append to the end of each output chunk.

Examples

export default {
  output: {
    footer: '/* End of bundle */',
  },
};

intro

Type: string | ((chunk: RenderedChunk) => string | Promise<string>)
Optional: Yes ✅
Path: output.intro

Code to prepend inside the wrapper function (after banner, before actual code).

Examples

export default {
  output: {
    format: 'iife',
    intro: 'const ENVIRONMENT = "production";',
  },
};

outro

Type: string | ((chunk: RenderedChunk) => string | Promise<string>)
Optional: Yes ✅
Path: output.outro

Code to append inside the wrapper function (after actual code, before footer).

Examples

export default {
  output: {
    format: 'iife',
    outro: 'console.log("Bundle loaded");',
  },
};

extend

Type: boolean
Default: false
Path: output.extend

When true, extends the global variable defined by the name option rather than overwriting it. Only applies to iife and umd formats.

Examples

export default {
  output: {
    format: 'umd',
    name: 'MyLib',
    extend: true,
  },
};

esModule

Type: boolean | 'if-default-prop'
Default: 'if-default-prop'
Path: output.esModule

Controls whether to add a __esModule: true property when generating CJS output.

Examples

export default {
  output: {
    format: 'cjs',
    esModule: true,
  },
};

In-depth

The available options:

false: Never add __esModule property
true: Always add __esModule: true property
'if-default-prop': Only add if there's a default export

assetFileNames

Type: string | ((chunkInfo: PreRenderedAsset) => string)
Default: 'assets/[name]-[hash][extname]'
Path: output.assetFileNames

Pattern for naming asset files (non-JavaScript files).

Placeholders: [name], [hash], [extname]

Examples

export default {
  output: {
    assetFileNames: 'assets/[name].[hash][extname]',
  },
};

entryFileNames

Type: string | ((chunkInfo: PreRenderedChunk) => string)
Default: '[name].js'
Path: output.entryFileNames

Pattern for naming entry chunk files.

Placeholders: [name], [hash], [ext]

Examples

export default {
  output: {
    entryFileNames: '[name]-[hash].js',
  },
};

chunkFileNames

Type: string | ((chunkInfo: PreRenderedChunk) => string)
Default: '[name]-[hash].js'
Path: output.chunkFileNames

Pattern for naming non-entry chunk files (code-split chunks).

Placeholders: [name], [hash], [ext]

Examples

export default {
  output: {
    chunkFileNames: 'chunks/[name].[hash].js',
  },
};

cssEntryFileNames

Type: string | ((chunkInfo: PreRenderedChunk) => string)
Default: '[name].css'
Path: output.cssEntryFileNames

Pattern for naming CSS entry files.

Placeholders: [name], [hash]

Examples

export default {
  output: {
    cssEntryFileNames: 'styles/[name]-[hash].css',
  },
};

cssChunkFileNames

Type: string | ((chunkInfo: PreRenderedChunk) => string)
Default: '[name]-[hash].css'
Path: output.cssChunkFileNames

Pattern for naming CSS chunk files (non-entry CSS files).

Placeholders: [name], [hash]

Examples

export default {
  output: {
    cssChunkFileNames: 'styles/chunks/[name].[hash].css',
  },
};

sanitizeFileName

Type: boolean | ((name: string) => string)
Default: true
Path: output.sanitizeFileName

Controls sanitization of file names to ensure they're valid across different file systems.

Examples

export default {
  output: {
    sanitizeFileName: (name) => {
      return name.replace(/[^a-zA-Z0-9.-]/g, '_');
    },
  },
};

In-depth

The available options:

false: Disable sanitization
true: Enable default sanitization
Function: Custom sanitization logic

minify

Type: boolean | 'dce-only' | MinifyOptions
Default: false
Path: output.minify

Control code minification.

Examples

export default {
  output: {
    minify: true,
  },
};

In-depth

The available options:

false: Disable minification
true: Enable full minification
'dce-only': Only dead code elimination
Object: Fine-grained minification settings

name

Type: string
Optional: Yes ✅
Path: output.name

The global variable name for the bundle. Required when using iife or umd format.

Examples

export default {
  output: {
    format: 'iife',
    name: 'MyLibrary',
  },
};

globals

Type: Record<string, string> | ((name: string) => string)
Optional: Yes ✅
Path: output.globals

Maps external module IDs to global variable names for iife and umd formats.

Examples

export default {
  external: ['react', 'react-dom'],
  output: {
    format: 'iife',
    name: 'MyApp',
    globals: {
      'react': 'React',
      'react-dom': 'ReactDOM',
    },
  },
};

paths

Type: Record<string, string> | ((id: string) => string)
Optional: Yes ✅
Path: output.paths

Maps external module IDs to paths. Useful for loading dependencies from CDNs.

Examples

export default {
  external: ['d3', 'lodash'],
  output: {
    paths: {
      'd3': 'https://cdn.jsdelivr.net/npm/d3@7',
      'lodash': 'https://cdn.jsdelivr.net/npm/lodash@4',
    },
  },
};

generatedCode

Type: Partial<GeneratedCodeOptions>
Default: {}
Path: output.generatedCode

Configuration for the generated code output. See output.generatedCode for nested options.

externalLiveBindings

Type: boolean
Default: true
Path: output.externalLiveBindings

When true, generates code that supports live bindings for external imports.

Examples

export default {
  output: {
    externalLiveBindings: false,
  },
};

inlineDynamicImports

Type: boolean
Default: true for 'iife' and 'umd' formats, false otherwise
Path: output.inlineDynamicImports

When true, dynamic imports are inlined into the main bundle instead of being split into separate chunks.

Examples

export default {
  output: {
    inlineDynamicImports: true,
  },
};

manualChunks

Type: (moduleId: string, meta: { getModuleInfo: (moduleId: string) => ModuleInfo | null }) => string | NullValue
Optional: Yes ✅
Path: output.manualChunks

Deprecated

This option is deprecated. Please use output.advancedChunks instead.

Allows manual control over chunk creation.

advancedChunks

Type: object
Optional: Yes ✅
Path: output.advancedChunks

Advanced chunking configuration. See output.advancedChunks for nested options.

legalComments

Type: 'none' | 'inline'
Default: 'inline'
Path: output.legalComments

Control comments in the output.

Examples

export default {
  output: {
    legalComments: 'inline',
  },
};

In-depth

The available options:

'none': Remove all comments
'inline': Preserve comments containing @license, @preserve, or starting with //! or /*!

polyfillRequire

Type: boolean
Default: true
Path: output.polyfillRequire

When true, adds a polyfill for require() function in non-CommonJS formats.

Examples

export default {
  output: {
    format: 'esm',
    polyfillRequire: true,
  },
};

hoistTransitiveImports

Type: boolean
Default: true
Path: output.hoistTransitiveImports

When false, prevents hoisting transitive imports to entry chunks.

Examples

export default {
  output: {
    hoistTransitiveImports: false,
  },
};

preserveModules

Type: boolean
Default: false
Path: output.preserveModules

When true, preserves the module structure instead of creating a single bundle.

Examples

export default {
  input: 'src/index.js',
  output: {
    dir: 'dist',
    preserveModules: true,
  },
};

virtualDirname

Type: string
Optional: Yes ✅
Path: output.virtualDirname

Virtual directory name for resolving __dirname and __filename in the output.

Examples

export default {
  output: {
    virtualDirname: '/virtual',
  },
};

preserveModulesRoot

Type: string
Optional: Yes ✅
Path: output.preserveModulesRoot

Base path to use when preserving modules. All preserved modules will be placed relative to this path.

Examples

export default {
  output: {
    dir: 'dist',
    preserveModules: true,
    preserveModulesRoot: 'src',
  },
};

topLevelVar

Type: boolean
Default: false
Path: output.topLevelVar

When true, uses var declarations at the top level instead of function expressions.

Examples

export default {
  output: {
    topLevelVar: true,
  },
};

cleanDir

Type: boolean
Default: false
Path: output.cleanDir

Clean the output directory (output.dir) before emitting output.

The cleanup happens before the generateBundle hook is called. This ensures that files created by plugins during generateBundle or writeBundle hooks are preserved.

Examples

export default {
  output: {
    cleanDir: true,
  },
};

In-depth

The timing of the directory cleanup is important for plugin compatibility:

The cleanup occurs before the generateBundle hook
Files created by plugins in generateBundle or writeBundle hooks are not deleted
If you have advanced use cases like multiple outputs with the same output.dir, consider using a separate cleanup script instead

minifyInternalExports

Type: boolean
Default: false
Path: output.minifyInternalExports

Whether to minify internal exports (exports not used by other chunks).

Examples

export default {
  output: {
    minifyInternalExports: true,
  },
};

keepNames

Type: boolean
Default: false
Path: output.keepNames

Preserve function and class names during bundling.

Examples

export default {
  output: {
    keepNames: true,
  },
};

In-depth

When enabled, the bundler will preserve the original names of functions and classes in the output, which is useful for:

Debugging and error stack traces
Code that relies on Function.prototype.name
Serialization that depends on constructor names

output ​

dir ​

Examples ​

file ​

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In-depth ​

exports ​

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hashCharacters ​

Examples ​

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format ​

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sourcemap ​

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banner ​

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footer ​

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intro ​

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outro ​

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extend ​

Examples ​

esModule ​

Examples ​

In-depth ​

assetFileNames ​

Examples ​

entryFileNames ​

Examples ​

chunkFileNames ​

Examples ​

cssEntryFileNames ​

Examples ​

cssChunkFileNames ​

Examples ​

sanitizeFileName ​

Examples ​

In-depth ​

minify ​

Examples ​

In-depth ​

name ​

Examples ​

globals ​

Examples ​

paths ​

Examples ​

generatedCode ​

externalLiveBindings ​

Examples ​

inlineDynamicImports ​

Examples ​

manualChunks ​

advancedChunks ​

legalComments ​

Examples ​

In-depth ​

polyfillRequire ​

Examples ​

hoistTransitiveImports ​

Examples ​

preserveModules ​

Examples ​

virtualDirname ​

Examples ​

preserveModulesRoot ​

Examples ​

topLevelVar ​

Examples ​

cleanDir ​

Examples ​

In-depth ​

minifyInternalExports ​

Examples ​

keepNames ​

output

dir

Examples

file

Examples

In-depth

exports

Examples

In-depth

hashCharacters

Examples

In-depth

format

Examples

In-depth

sourcemap

Examples

banner

Examples

footer

Examples

intro

Examples

outro

Examples

extend

Examples

esModule

Examples

In-depth

assetFileNames

Examples

entryFileNames

Examples

chunkFileNames

Examples

cssEntryFileNames

Examples

cssChunkFileNames

Examples

sanitizeFileName

Examples

In-depth

minify

Examples

In-depth

name

Examples

globals

Examples

paths

Examples

generatedCode

externalLiveBindings

Examples

inlineDynamicImports

Examples

manualChunks

advancedChunks

legalComments

Examples

In-depth

polyfillRequire

Examples

hoistTransitiveImports

Examples

preserveModules

Examples

virtualDirname

Examples

preserveModulesRoot

Examples

topLevelVar

Examples

cleanDir

Examples

In-depth

minifyInternalExports

Examples

keepNames