rollup.config.js

import commonjs from '@rollup/plugin-commonjs'
import { nodeResolve } from '@rollup/plugin-node-resolve'
import typescript from '@rollup/plugin-typescript'
import dts from 'rollup-plugin-dts'
import { terser } from 'rollup-plugin-terser'

const output = (format) => {
  const base = {
    file: `dist/${format}.js`,
    format,
    sourcemap: true,
    name: 'markerClusterer', // Only needed for UMD, but doesn't hurt the other outputs, so leaving it here for simplicity.
    globals: {
      react: 'React',
      'react-dom': 'ReactDOM',
    },
  }

  return [
    // We need the base output
    base,

    // And also a minified version
    { ...base, file: `dist/${format}.min.js`, plugins: [terser()] },
  ]
}

export default [
  {
    plugins: [typescript(), nodeResolve(), commonjs()],
    external: ['react', 'react-dom'],

    input: 'src/index.ts',
    output: [...output('cjs'), ...output('umd'), ...output('esm')],
  },
  {
    input: 'src/index.ts',
    output: [{ file: 'dist/index.d.ts', format: 'es' }],
    plugins: [dts()],
  },
]