Multiple output files with rollup

rollup.config.js

import babel from 'rollup-plugin-babel';
import commonjs from 'rollup-plugin-commonjs';
import external from 'rollup-plugin-peer-deps-external';
import postcss from 'rollup-plugin-postcss';
import resolve from 'rollup-plugin-node-resolve';
import url from 'rollup-plugin-url';
import autoprefixer from 'autoprefixer';
import json from 'rollup-plugin-json';
import filesize from 'rollup-plugin-filesize';
import globby from 'globby';

const plugins = [
  external(),
  postcss({
    plugins: [
      autoprefixer({
        browsers: [
          '>1%',
          'last 4 versions',
          'Firefox ESR',
          'iOS >= 8',
          'not ie < 12',
          'not ie_mob < 12'
        ]
      }),
    ],
  }),
  url(),
  json(),
  babel({
    exclude: 'node_modules/**',
    plugins: ['external-helpers'],
  }),
  resolve(),
  commonjs(),
  filesize()
];

const capitalizeComponent = (name) => {
  const splitName = name.split('-');
  const componentName = splitName.map(str => `${str.charAt(0).toUpperCase()}${str.slice(1)}`);
  return componentName.join('');
}

async function getFiles() {
  const paths = await globby(['src/components/**/index.js', '!**/__tests__']);

  const exports = paths.map(path => {
    const fileSearchArr = path.match('/(?<=components/).*(?=/)/');
    const componentName = capitalizeComponent(fileSearchArr[0].replace(/[/]/g, ''));
    
    return {
      input: path,
      output: [
        {
          file: `${componentName}.js`,
          format: 'cjs',
          sourcemap: true,
          exports: 'named'
        },
        {
          file: `${componentName}.es.js`,
          format: 'es',
          sourcemap: true,
          exports: 'named'
        }
      ],
      plugins
    }
  })
  return exports;
}

export default getFiles();

If you have packages that are in-use in the library and your project make sure to add external option
external: ['whatever-the-package-is', 'maybe-another']

Otherwise it'll add your package to the build and bloat the size up.