webpack.config.js

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

module.exports = {
  entry: ['./assets/js/index.js', './assets/stylesheets/index.scss'],
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  },
  module: {
    rules: [
      {
        test: /\.scss$/,
        use: [
            process.env.NODE_ENV !== 'production' ? 'style-loader' : MiniCssExtractPlugin.loader,
            "css-loader", // translates CSS into CommonJS
            "sass-loader" // compiles Sass to CSS, using Node Sass by default
        ]
      },
      {
        test: /\.m?js$/,
        exclude: /(node_modules)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
        filename: "[name].css",
        chunkFilename: "[id].css"
    })
  ],
  devServer: {
    contentBase: path.join(__dirname, 'dist'),
    port: 8080
  }
};