.rollup.js

import babel from '@rollup/plugin-babel';
import commonjs from '@rollup/plugin-commonjs';
import { nodeResolve } from '@rollup/plugin-node-resolve';

export default [
	{
		input: 'src/index.js',
		output: [
			{ file: 'dist/index.cjs', format: 'cjs', sourcemap: true, exports: 'default' },
			{ file: 'dist/index.mjs', format: 'esm', sourcemap: true, exports: 'default' }
		],
		plugins: [
			commonjs(),
			nodeResolve({
				resolveOnly: [
					'cssesc',
					'postcss-selector-parser',
					'util-deprecate',
				]
			}),
			babel({
				babelHelpers: 'bundled',
				exclude: 'node_modules/**',
				presets: [
					['@babel/preset-env', {
						corejs: 3,
						loose: true,
						modules: false,
						targets: { node: 12 },
						useBuiltIns: 'usage'
					}]
				]
			}),
		]
	},
	{
		input: 'src/index.js',
		output: [
			{ file: 'dist/index.deno.mjs', format: 'esm', sourcemap: true, exports: 'default' }
		],
		plugins: [
			commonjs(),
			nodeResolve({
				browser: true,
				resolveOnly: [
					'cssesc',
					'postcss-selector-parser',
					'util-deprecate',
				]
			}),
			babel({
				babelHelpers: 'bundled',
				exclude: 'node_modules/**',
				presets: [
					['@babel/preset-env', {
						corejs: 3,
						loose: true,
						modules: false,
						targets: { node: 12 },
						useBuiltIns: 'usage'
					}]
				]
			}),
		]
	}
]