gem-hunter

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

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

Using npm:

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

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.

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.

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'].

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

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

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

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.

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';

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

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

Type: String
Default: '/'

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

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.

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

Type: Boolean
Default: false

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

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')

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(), '..')

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.

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.

This plugin honours the rollup preserveSymlinks option.

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()]
};

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: ...
})

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 } }
});

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.

CONTRIBUTING

LICENSE (MIT)