webpack.config.js

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

const config = {
  entry: [
    path.resolve(__dirname, "src", "index.js"),
    path.resolve(__dirname, "src", "index.scss"),
  ],
  output: {
    path: path.join(__dirname, "dist"),
    filename: "[name].js",
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        use: ["babel-loader"],
        exclude: /node_modules/,
      },
      {
        test: /\.s?[ac]ss$/,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: "css-loader",
            options: { url: false },
          },
          "sass-loader",
        ],
      },
    ],
  },
  plugins: [new MiniCssExtractPlugin()],
};

module.exports = (env, argv) => {
  if (argv.mode === "production") {
    config.devtool = "source-map";
  } else {
    config.devtool = "eval-source-map";
  }

  return config;
};