webpack.config.js

var path = require('path');
var MiniCssExtractPlugin = require('mini-css-extract-plugin')

module.exports = {
  mode: 'production',
  entry: path.join(__dirname, 'example/src/index.jsx'),
  output: {
    path: path.join(__dirname, 'example/assets'),
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        loader: 'babel-loader',
      },
      {
        test: /\.css$/,
        include: path.join(__dirname),
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
          },
          'css-loader'
        ]
      },
    ],
  },
  resolve: {
    extensions: ['.js', '.jsx'],
  },
  plugins: [
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // both options are optional
      filename: 'bundle.css',
      chunkFilename: '[id].css'
    })
  ],
};