@rollup/plugin-node-resolve

What is @rollup/plugin-node-resolve?

The @rollup/plugin-node-resolve package is a plugin for Rollup that allows it to resolve node_modules on your behalf, similar to how Node.js would work. It helps in bundling packages with Rollup by locating and bundling third-party dependencies from the node_modules directory.

What are @rollup/plugin-node-resolve's main functionalities?

Resolving modules from node_modules

Automatically resolves modules from the node_modules directory, allowing you to import dependencies in your project.

import resolve from '@rollup/plugin-node-resolve';

export default {
  plugins: [
    resolve()
  ]
};

Custom resolution for specific modules

Allows you to specify custom resolution options for modules, such as looking in different directories.

import resolve from '@rollup/plugin-node-resolve';

export default {
  plugins: [
    resolve({
      customResolveOptions: {
        moduleDirectory: 'custom_modules'
      }
    })
  ]
};

Browser field support for package.json

Respects the 'browser' field in package.json when bundling packages, which can specify alternative files to load for certain environments.

import resolve from '@rollup/plugin-node-resolve';

export default {
  plugins: [
    resolve({
      browser: true
    })
  ]
};

Main fields configuration

Allows configuration of which fields in package.json files it should look at when trying to resolve an import.

import resolve from '@rollup/plugin-node-resolve';

export default {
  plugins: [
    resolve({
      mainFields: ['module', 'main']
    })
  ]
};

Other packages similar to @rollup/plugin-node-resolve

webpack

Webpack is a powerful module bundler that comes with its own resolution mechanism similar to @rollup/plugin-node-resolve. It resolves modules by default and can be configured extensively via its configuration file.

browserify

Browserify is another bundler that allows you to require('modules') in the browser by bundling up all of your dependencies. It also has a resolution mechanism similar to Node.js, much like @rollup/plugin-node-resolve.

parcel-bundler

Parcel is a web application bundler that has zero configuration by default and includes a powerful module resolution system that works out of the box, similar to @rollup/plugin-node-resolve.

README

@rollup/plugin-node-resolve

🍣 A Rollup plugin which locates modules using the Node resolution algorithm, for using third party modules in node_modules

Requirements

This plugin requires an LTS Node version (v14.0.0+) and Rollup v2.78.0+.

Install

Using npm:

npm install @rollup/plugin-node-resolve --save-dev

Usage

Create a rollup.config.js configuration file and import the plugin:

import { nodeResolve } from '@rollup/plugin-node-resolve';

export default {
  input: 'src/index.js',
  output: {
    dir: 'output',
    format: 'cjs'
  },
  plugins: [nodeResolve()]
};

Then call rollup either via the CLI or the API.

Package entrypoints

This plugin supports the package entrypoints feature from node js, specified in the exports or imports field of a package. Check the official documentation for more information on how this works. This is the default behavior. In the abscence of these fields, the fields in mainFields will be the ones to be used.

Options

exportConditions

Type: Array[...String]
Default: []

Additional conditions of the package.json exports field to match when resolving modules. By default, this plugin looks for the ['default', 'module', 'import'] conditions when resolving imports.

When using @rollup/plugin-commonjs v16 or higher, this plugin will use the ['default', 'module', 'require'] conditions when resolving require statements.

Setting this option will add extra conditions on top of the default conditions. See https://nodejs.org/api/packages.html#packages_conditional_exports for more information.

In order to get the resolution behavior of Node.js, set this to ['node'].

browser

Type: Boolean
Default: false

If true, instructs the plugin to use the browser module resolutions in package.json and adds 'browser' to exportConditions if it is not present so browser conditionals in exports are applied. If false, any browser properties in package files will be ignored. Alternatively, a value of 'browser' can be added to both the mainFields and exportConditions options, however this option takes precedence over mainFields.

This option does not work when a package is using package entrypoints

moduleDirectories

Type: Array[...String]
Default: ['node_modules']

A list of directory names in which to recursively look for modules.

modulePaths

Type: Array[...String]
Default: []

A list of absolute paths to additional locations to search for modules. This is analogous to setting the NODE_PATH environment variable for node.

dedupe

Type: Array[...String]
Default: []

An Array of modules names, which instructs the plugin to force resolving for the specified modules to the root node_modules. Helps to prevent bundling the same package multiple times if package is imported from dependencies.

dedupe: ['my-package', '@namespace/my-package'];

This will deduplicate bare imports such as:

import 'my-package';
import '@namespace/my-package';

And it will deduplicate deep imports such as:

import 'my-package/foo.js';
import '@namespace/my-package/bar.js';

extensions

Type: Array[...String]
Default: ['.mjs', '.js', '.json', '.node']

Specifies the extensions of files that the plugin will operate on.

jail

Type: String
Default: '/'

Locks the module search within specified path (e.g. chroot). Modules defined outside this path will be ignored by this plugin.

mainFields

Type: Array[...String]
Default: ['module', 'main']
Valid values: ['browser', 'jsnext:main', 'module', 'main']

Specifies the properties to scan within a package.json, used to determine the bundle entry point. The order of property names is significant, as the first-found property is used as the resolved entry point. If the array contains 'browser', key/values specified in the package.json browser property will be used.

preferBuiltins

Type: Boolean | (module: string) => boolean
Default: true (with warnings if a builtin module is used over a local version. Set to true to disable warning.)

If true, the plugin will prefer built-in modules (e.g. fs, path). If false, the plugin will look for locally installed modules of the same name.

Alternatively, you may pass in a function that returns a boolean to confirm whether the plugin should prefer built-in modules. e.g.

preferBuiltins: (module) => module !== 'punycode';

will not treat punycode as a built-in module

modulesOnly

Type: Boolean
Default: false

If true, inspect resolved files to assert that they are ES2015 modules.

resolveOnly

Type: Array[...String|RegExp] | (module: string) => boolean
Default: null

An Array which instructs the plugin to limit module resolution to those whose names match patterns in the array. Note: Modules not matching any patterns will be marked as external.

Alternatively, you may pass in a function that returns a boolean to confirm whether the module should be included or not.

Examples:

• resolveOnly: ['batman', /^@batcave\/.*$/]
• resolveOnly: module => !module.includes('joker')

rootDir

Type: String
Default: process.cwd()

Specifies the root directory from which to resolve modules. Typically used when resolving entry-point imports, and when resolving deduplicated modules. Useful when executing rollup in a package of a mono-repository.

// Set the root directory to be the parent folder
rootDir: path.join(process.cwd(), '..')

ignoreSideEffectsForRoot

If you use the sideEffects property in the package.json, by default this is respected for files in the root package. Set to true to ignore the sideEffects configuration for the root package.

allowExportsFolderMapping

Older Node versions supported exports mappings of folders like

{
  "exports": {
    "./foo/": "./dist/foo/"
  }
}

This was deprecated with Node 14 and removed in Node 17, instead it is recommended to use exports patterns like

{
  "exports": {
    "./foo/*": "./dist/foo/*"
  }
}

But for backwards compatibility this behavior is still supported by enabling the allowExportsFolderMapping (defaults to true). The default value might change in a futur major release.

Preserving symlinks

This plugin honours the rollup preserveSymlinks option.

Using with @rollup/plugin-commonjs

Since most packages in your node_modules folder are probably legacy CommonJS rather than JavaScript modules, you may need to use @rollup/plugin-commonjs:

// rollup.config.js
import { nodeResolve } from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';

export default {
  input: 'main.js',
  output: {
    file: 'bundle.js',
    format: 'iife',
    name: 'MyModule'
  },
  plugins: [nodeResolve(), commonjs()]
};

Resolving Built-Ins (like fs)

By default this plugin will prefer built-ins over local modules, marking them as external.

See preferBuiltins.

To provide stubbed versions of Node built-ins, use a plugin like rollup-plugin-node-polyfills and set preferBuiltins to false. e.g.

import { nodeResolve } from '@rollup/plugin-node-resolve';
import nodePolyfills from 'rollup-plugin-node-polyfills';
export default ({
  input: ...,
  plugins: [
    nodePolyfills(),
    nodeResolve({ preferBuiltins: false })
  ],
  external: builtins,
  output: ...
})

Resolving Require Statements

According to NodeJS module resolution require statements should resolve using the require condition in the package exports field, while es modules should use the import condition.

The node resolve plugin uses import by default, you can opt into using the require semantics by passing an extra option to the resolve function:

this.resolve(importee, importer, {
  skipSelf: true,
  custom: { 'node-resolve': { isRequire: true } }
});

Resolve Options

After this plugin resolved an import id to its target file in node_modules, it will invoke this.resolve again with the resolved id. It will pass the following information in the resolve options:

this.resolve(resolved.id, importer, {
  custom: {
    'node-resolve': {
      resolved, // the object with information from node.js resolve
      importee // the original import id
    }
  }
});

Your plugin can use the importee information to map an original import to its resolved file in node_modules, in a plugin hook such as resolveId.

The resolved object contains the resolved id, which is passed as the first parameter. It also has a property moduleSideEffects, which may contain the value from the npm package.json field sideEffects or null.

Meta

CONTRIBUTING

LICENSE (MIT)