webpack.prod.js

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

const commonConfig = require('./webpack.common.js');

module.exports = merge(commonConfig, {
    mode: 'production',
    devtool: 'source-map',

    plugins: [
        new MiniCssExtractPlugin({
            filename: '[name].[contenthash].css',
        }),
    ],

    module: {
        rules: [
            {
                test: /\.s[ac]ss$/i,
                use: [
                    {
                        loader: MiniCssExtractPlugin.loader,
                    },
                    {
                        loader: 'css-loader',
                        options: { sourceMap: true },
                    },
                    {
                        loader: 'sass-loader',
                        options: { sourceMap: true },
                    },
                ],
            },
            {
                test: /\.css$/,
                use: [MiniCssExtractPlugin.loader, 'css-loader'],
            },
        ],
    },

    optimization: {
        minimize: true,
        minimizer: [
            new CssMinimizerPlugin(),
            new TerserPlugin({
                parallel: true,
            }),
        ],
    },
});