rollup.config.js

import path from 'path'
import babel from '@rollup/plugin-babel'
import resolve from '@rollup/plugin-node-resolve'
import { terser } from 'rollup-plugin-terser'

const root = process.platform === 'win32' ? path.resolve( '/' ) : '/'
const external = ( id ) => !id.startsWith( '.' ) && !id.startsWith( root )
const extensions = [ '.js', '.jsx', '.ts', '.tsx', '.json' ]

const getBabelOptions = ({ useESModules }, targets ) => ({
	babelrc: false,
	extensions,
	exclude: '**/node_modules/**',
	babelHelpers: 'runtime',
	presets: [
		[ '@babel/preset-env', { loose: true, modules: false, targets }],
		'@babel/preset-react',
		'@babel/preset-typescript',
	],
	plugins: [ [ '@babel/transform-runtime', { regenerator: false, useESModules }] ],
})

export default [
	{
		input: './src/use-subscription.ts',
		output: { file: 'dist/index.js', format: 'esm', exports: 'named' },
		external,
		plugins: [
			babel( getBabelOptions({ useESModules: true }, '>1%, not dead, not ie 11, not op_mini all' ) ),
			resolve({ extensions }),
			terser(),
		],
	},
	{
		input: './src/use-subscription.ts',
		output: { file: 'dist/index.cjs.js', format: 'cjs', exports: 'named' },
		external,
		plugins: [
			babel( getBabelOptions({ useESModules: false }) ),
			resolve({ extensions }),
			terser(),
		],
	},
]