rollup.config.js

import {terser} from 'rollup-plugin-terser';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import babel from '@rollup/plugin-babel';
import postcss from 'rollup-plugin-postcss';
import postcssPresetEnv from 'postcss-preset-env/index.js';

process.chdir(__dirname);

module.exports = {
  input: './index.js',
  output: {
    file: './js/dist/form.min.js',
    name: 'Form',
    format: 'umd'
  },
  plugins: [
    postcss(
      {
        extract: true,
        minimize: true,
        plugins: [
          postcssPresetEnv({browsers: ['defaults', 'not ie > 0']}),
        ],
      }),
    resolve({browser: true, preferBuiltins: false}),
    commonjs(),
    terser(),
    babel(
      {
        babelHelpers: 'bundled',
        babelrc: false,
        exclude: [/\/core-js\//],
        presets: [
          [
            '@babel/preset-env',
            {
              corejs: 3,
              modules: false,
              useBuiltIns: 'usage',
              targets: ['defaults', 'not ie > 0'],
            },
          ],
        ],
      }),
  ]
};