codex.docs/webpack.config.js

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

/**
 * Options for the Babel
 */
const babelLoader = {
  loader: 'babel-loader',
  options: {
    cacheDirectory: '.cache/babel-loader',
    presets: [
      [
        '@babel/preset-env',
        {
          'useBuiltIns': 'usage'
        }
      ]
    ],
    plugins: [
      '@babel/plugin-syntax-dynamic-import'
    ]
  }
};

module.exports = (env) => {
  return {
    output: {
      libraryExport: 'default' // uses to export .default field of app.js exported class instance
    },
    module: {
      rules: [
        {
          test: /\.p?css$/,
          use: [
            {
              loader: MiniCssExtractPlugin.loader,
              options: {
                // you can specify a publicPath here
                // by default it use publicPath in webpackOptions.output
                publicPath: '../'
              }
            },
            {
              loader: 'css-loader',
              options: {
                importLoaders: 1
              }
            },
            {
              loader: 'postcss-loader',
              options: {
                config: {
                  path: './src/frontend/'
                }
              }
            }
          ]
        }, {
          test: /\.js$/,
          exclude: /(node_modules|bower_components)/,
          use: [
            babelLoader
          ]
        }
      ]
    },
    plugins: [
      new MiniCssExtractPlugin({
        // Options similar to the same options in webpackOptions.output
        filename: '[name].css'
      })
    ],
    optimization: {
      splitChunks: false
    }
  };
};