rollup.config.js

import ts from 'rollup-plugin-ts'; // Prefered over @rollup/plugin-typescript as it bundles .d.ts files
import json from '@rollup/plugin-json';
import { banner } from '../../banner';

import pkg from './package.json';

import { builtinModules } from 'module';

export default [
  // CommonJS (for Node) and ES module (for bundlers) build.
  {
    input: 'src/index.ts',
    external: [...builtinModules, ...Object.keys(pkg.dependencies), ...Object.keys(pkg.devDependencies)],
    plugins: [
      json(),
      ts({ browserslist: false }), // so Rollup can convert TypeScript to JavaScript
      banner(true),
    ],
    output: [
      { file: pkg.main, format: 'cjs', sourcemap: true },
      { file: pkg.module, format: 'es', sourcemap: true },
    ],
  },
];