rollup-plugin-node-externals

A Rollup/Vite plugin that automatically declares NodeJS built-in modules as external. Also handles npm dependencies, devDependencies, peerDependencies and optionalDependencies.

Works in npm/yarn/pnpm/lerna monorepos too!

Why you need this

Installation

Use your favorite package manager. Mine is npm.

npm install --save-dev rollup-plugin-node-externals

Usage

Import

The plugin is available both as the default export and as a named export:

import nodeExternals from 'rollup-plugin-node-externals'

and

import { nodeExternals } from 'rollup-plugin-node-externals'

will both work.

Options

You generally want to have your runtime dependencies (those that will be imported/required at runtime) listed under dependencies in package.json, and your development dependencies (those that should be bundled in by Rollup) listed under devDependencies.

If you follow this simple rule, then the default settings are just what you need:

// rollup.config.js

export default {
  ...
  plugins: [
    nodeExternals(),
  ]
}

This will bundle your devDependencies in while leaving your dependencies, peerDependencies and optionalDependencies external.

Should the defaults not suit your case, here is the full list of options.

import nodeExternals from 'rollup-plugin-node-externals'

export default {
  ...
  plugins: [
    nodeExternals({

      // Make node builtins external. Default: true.
      builtins?: boolean

      // node: prefix handing for importing Node builtins. Default: 'add'.
      builtinsPrefix?: 'add' | 'strip' | 'ignore'

      // The path(s) to your package.json. See below for default.
      packagePath?: string | string[]

      // Make pkg.dependencies external. Default: true.
      deps?: boolean

      // Make pkg.devDependencies external. Default: false.
      devDeps?: boolean

      // Make pkg.peerDependencies external. Default: true.
      peerDeps?: boolean

      // Make pkg.optionalDependencies external. Default: true.
      optDeps?: boolean

      // Modules to force include in externals. Default: [].
      include?: string | RegExp | (string | RegExp)[]

      // Modules to force exclude from externals. Default: [].
      exclude?: string | RegExp | (string | RegExp)[]
    })
  ]
}

builtins?: boolean = true

Set the builtins option to false if you'd like to use some shims/polyfills for those. You'll most certainly need an other plugin as well.

builtinsPrefix?: 'add' | 'strip' | 'ignore' = 'add'

How to handle the node: scheme used in recent versions of Node (i.e., import path from 'node:path').

• If add (the default, recommended), the node: scheme is always added. In effect, this dedupes your imports of Node builtins by homogenizing their names to their schemed version.
• If strip, the scheme is always removed. In effect, this dedupes your imports of Node builtins by homogenizing their names to their unschemed version. Schemed-only builtins like node:test are not stripped.
• ignore will simply leave all builtins imports as written in your code. > Note that scheme handling is always applied, regardless of the builtins options being enabled or not.

packagePath?: string | string[] = []

If you're working with monorepos, the packagePath option is made for you. It can take a path, or an array of paths, to your package.json file(s). If not specified, the default is to start with the current directory's package.json then go up scan for all package.json files in parent directories recursively until either the root git directory is reached, the root of the monorepo is reached, or no other package.json can be found.

deps?: boolean = true
devDeps?: boolean = false
peerDeps?: boolean = true
optDeps?: boolean = true

Set the deps, devDeps, peerDeps and optDeps options to false to prevent the corresponding dependencies from being externalized, therefore letting Rollup bundle them with your code.

include?: string | RegExp | (string | RegExp)[] = []

Use the include option to force certain dependencies into the list of externals, regardless of other settings:

nodeExternals({
  deps: false,                // Deps will be bundled in
  include: 'fsevents'         // Except for fsevents
})

exclude?: string | RegExp | (string | RegExp)[] = []

Conversely, use the exclude option to remove certain dependencies from the list of externals, regardless of other settings:

nodeExternals({
  deps: true,                 // Keep deps external
  exclude: 'electron-reload'  // Yet we want `electron-reload` bundled in
})

Notes

1/ This plugin is smart

• Falsy values in include and exclude are silently ignored. This allows for conditional constructs like exclude: process.env.NODE_ENV === 'production' && 'my-prod-only-dep'.
• Subpath imports are supported with regexes, meaning that include: /^lodash/ will externalize lodash and also lodash/map, lodash/merge, etc.

2/ This plugin is not that smart

It uses an exact match against your imports as written in your code. No resolving of path aliases or substitutions is made:

// In your code, say '@/lib' is an alias for source/deep/path/to/some/lib:
import something from '@/lib'

If you don't want lib bundled in, then write:

// In rollup.config.js:
nodeExternals({
    include: '@/lib'
})

3/ Order matters

If you're also using @rollup/plugin-node-resolve, make sure this plugin comes before it in the plugins array:

import nodeExternals from 'rollup-plugin-node-externals'
import nodeResolve from '@rollup/plugin-node-resolve'

export default {
  ...
  plugins: [
    nodeExternals(),
    nodeResolve(),
  ]
}

Note that as of version 7, this plugin's resolveId hook has a order: 'pre' property that will make Rollup call it very early in the module resolution process. Nevertheless, it is best to always make this plugin the first one in the plugins array.

4/ Rollup rules

Rollup's own external configuration option always takes precedence over this plugin. This is intentional.

5/ Using with Vite

While this plugin has always been compatible with Vite, it was previously necessary to use the following vite.config.js to make it work reliably in every situation:

import { defineConfig } from 'vite'
import nodeExternals from 'rollup-plugin-node-externals'

export default defineConfig({
  ...
  plugins: [
    { enforce: 'pre', ...nodeExternals() },
    // other plugins follow
  ]
})

Since version 7.1, this is no longer necessary and you can use the normal syntax instead. You still want to keep this plugin early in the plugins array, though.

import { defineConfig } from 'vite'
import nodeExternals from 'rollup-plugin-node-externals'

export default defineConfig({
  ...
  plugins: [
    nodeExternals()
    // other plugins follow
  ]
})

Breaking changes

Breaking changes in version 7

• This package now only supports the Maintenance, LTS and Current versions of Node.js.
• The previously undocumented externals named export has been removed.

Breaking changes in previous versions

Licence

MIT