rollup.config.js

import babel from '@rollup/plugin-babel'
import commonjs from '@rollup/plugin-commonjs'
import nodeResolve from '@rollup/plugin-node-resolve'
import pkg from './package.json' with { type: 'json' }
import replace from '@rollup/plugin-replace'
import terser from '@rollup/plugin-terser'

const { dependencies, exports, unpkg } = pkg

export default process.env.NODE_ENV === 'cjs'
    ? {
        input: 'src/index.js',
        external: new RegExp(`^(${Object.keys(dependencies).join('|')})`),
        output: {
            file: exports['.'].require,
            format: 'cjs',
        },
        plugins: [
            babel({ babelHelpers: 'runtime' }),
            commonjs(),
        ],
    }
    : {
        input: 'src/index.js',
        output: {
            file: unpkg,
            format: 'umd',
            name: 'animate',
        },
        plugins: [
            replace({ 'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV) }),
            nodeResolve(),
            babel({ babelHelpers: 'bundled' }),
            commonjs(),
            terser({ keep_fnames: /play|pause/ }),
        ],
    }