Automatically externalize peerDependencies in a rollup bundle.

When bundling a library using rollup, we generally want to keep from including peerDependencies since they are expected to be provided by the consumer of the library. By excluding these dependencies, we keep bundle size down and avoid bundling duplicate dependencies.

We can achieve this using the rollup external configuration option, providing it a list of the peer dependencies to exclude from the bundle. This plugin automates the process, automatically adding a library's peerDependencies to the external configuration.

npm install --save-dev rollup-plugin-peer-deps-external

// Add to plugins array in rollup.config.js
import peerDepsExternal from 'rollup-plugin-peer-deps-external';

export default {
  plugins: [
    // Preferably set as first plugin.
    peerDepsExternal(),
  ],
}

If your package.json is not in the current working directory you can specify the path to the file

// Add to plugins array in rollup.config.js
import peerDepsExternal from 'rollup-plugin-peer-deps-external';

export default {
  plugins: [
    // Preferably set as first plugin.
    peerDepsExternal({
      packageJsonPath: 'my/folder/package.json'
    }),
  ],
}

Set includeDependencies to true to also externalize regular dependencies in addition to peer deps.

// Add to plugins array in rollup.config.js
import peerDepsExternal from 'rollup-plugin-peer-deps-external';

export default {
  plugins: [
    // Preferably set as first plugin.
    peerDepsExternal({
      includeDependencies: true,
    }),
  ],
}

This plugin is compatible with module path format applied by, for example, babel-plugin-lodash. For any module name in peerDependencies, all paths beginning with that module name will also be added to external.

E.g.: If lodash is in peerDependencies, an import of lodash/map would be added to externals.