webpack.config.js

const TerserJSPlugin = require("terser-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");

const config = {
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
        },
      },
      {
        test: /\.s?css$/,
        use: [
          MiniCssExtractPlugin.loader,
          "css-loader",
          "postcss-loader",
          "sass-loader",
        ],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: "main.css",
    }),
  ],
};

if (process.env.NODE_ENV === "production") {
  config.optimization = {
    minimizer: [new TerserJSPlugin({}), new OptimizeCSSAssetsPlugin({})],
  };
} else {
  config.devtool = "eval-source-map";
}

module.exports = config;