webpack.config.js

const MODE = 'development';
const enabledSourceMap = (MODE === 'development');

module.exports = {
  entry: "./src/index.js",
  devServer: {
    contentBase: "dist",
    port: 8080
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        use: [
          {
            loader: "babel-loader",
            options: {
              presets: ["@babel/preset-env"]
            }
          }
        ]
      },{
        test: /\.scss$/,
        use: [
          'style-loader',
          {
            loader: 'css-loader',
            options: {
              url: false,
              sourceMap: enabledSourceMap,
              // 0 => no loaders (default);
              // 1 => postcss-loader;
              // 2 => postcss-loader, sass-loader
              importLoaders: 2
            },
          },
          {
            loader: 'sass-loader',
            options: {
              sourceMap: enabledSourceMap,
            }
          }
        ]
    }
    ]
  }
};