rollup.config.js

import babel from 'rollup-plugin-babel'
import uglify from 'rollup-plugin-uglify'
import resolve from 'rollup-plugin-node-resolve'

const { BUILD_ENV, BUILD_FORMAT } = process.env

const config = {
  input: 'src/index.js',
  output: {
    name: 'withSideEffect',
    globals: {
      react: 'React',
    },
  },
  plugins: [
    babel({
      runtimeHelpers: true,
      babelrc: false,
      presets: [
        '@babel/preset-react',
        ['@babel/preset-env', { loose: true, modules: false }]
      ],
      plugins: [
        ['@babel/plugin-transform-runtime', {
          useESModules: BUILD_FORMAT === 'es' || BUILD_FORMAT === 'umd'
        }],
        '@babel/plugin-proposal-object-rest-spread',
        '@babel/plugin-proposal-class-properties'
      ],
      exclude: 'node_modules/**',
    }),
  ],
  external: ['react', 'exenv'],
}

if (BUILD_FORMAT === 'umd') {
  // In the browser build, include our smaller dependencies
  // so users only need to include React
  config.external = ['react']
  config.plugins.push(
    resolve(),
  )
}

if (BUILD_ENV === 'production') {
  config.plugins.push(uglify())
}

export default config