webpack.config.prod.js

const { merge } = require("webpack-merge");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const OptimizeCssAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const TerserPlugin = require("terser-webpack-plugin");
const commonConfig = require("./webpack.config.common");

module.exports = merge(commonConfig, {
  mode: "production",
  devtool: "source-map",
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [MiniCssExtractPlugin.loader, "css-loader"],
      },
      {
        test: /\.s[ac]ss$/i,
        use: [
          MiniCssExtractPlugin.loader,
          // Translates CSS into CommonJS
          "css-loader",
          // Compiles Sass to CSS
          "sass-loader",
        ],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: "[name].[contenthash].css",
    }),
  ],
  optimization: {
    minimize: true,
    minimizer: [
      new OptimizeCssAssetsPlugin({
        cssProcessorOptions: {
          map: {
            inline: false,
            annotation: true,
          },
        },
      }),
      new TerserPlugin({
        // Use multi-process parallel running to improve the build speed
        // Default number of concurrent runs: os.cpus().length - 1
        parallel: true,
        // Enable file caching
        terserOptions: {
          sourceMap: true,
        },
      }),
    ],
  },
});