webpack.prod.js

const { merge } = require('webpack-merge');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const TerserPlugin = require('terser-webpack-plugin');
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
const common = require('./webpack.common');

module.exports = merge(common, {
  mode: 'production',
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin(),
      new CssMinimizerPlugin(),
    ],
    splitChunks: {
      cacheGroups: {
        styles: {
          name: 'main',
          test: /\.(css|scss)$/,
          chunks: 'all',
        },
      },
    },
  },
  module: {
    rules: [
      {
        test: /\.(css|scss)$/,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: 'css-loader',
            options: {
              importLoaders: 2,
            },
          },
          'postcss-loader',
          'sass-loader',
        ],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: '[name].css',
    }),
  ],
});