webpack.config.prod.js

const path = require('path');
const nodeExternals = require('webpack-node-externals');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CopyPlugin = require('copy-webpack-plugin');

module.exports = {
  entry: './src/index.js',
  mode: 'none',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
    libraryTarget: 'commonjs2'
  },
  plugins: [
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // both options are optional
      filename: "[name].css",
      chunkFilename: "[id].css"
    }),
    new CopyPlugin([
      { from: 'index.d.ts', to: 'bundle.d.ts' },
    ]),
  ],
  module: {
    rules: [
      {
        test: /\.js$/,
        use: 'babel-loader',
        exclude: /node_modules/
      },
      {
        test: /\.css$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
            options: {
              // you can specify a publicPath here
              // by default it use publicPath in webpackOptions.output
              publicPath: '../'
            }
          },
          'css-loader'
        ]
      },
    ]
  },
  externals: [nodeExternals()],
};