webpack.config.js

const webpack = require('webpack');

module.exports = {
  entry: ['@babel/polyfill', 'react-hot-loader/patch', './dev/index.js'],
  output: {
    filename: 'bundle.js',
  },
  mode: 'development',
  module: {
    rules: [
      {
        test: /\.js?$/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/react', '@babel/env'],
            plugins: [
              'react-hot-loader/babel',
              '@babel/plugin-proposal-object-rest-spread',
              [
                'module-resolver',
                {
                  root: ['./'],
                  alias: {
                    components: './src/components',
                    lib: './src/lib',
                    styles: './src/styles',
                  },
                },
              ],
            ],
          },
        },
        exclude: [/node_modules/],
      },
      {
        test: /\.(css|scss)?$/,
        use: ['style-loader', 'css-loader', 'sass-loader'],
      },
    ],
  },
  resolve: {
    alias: {
      'react-dom': '@hot-loader/react-dom',
    },
  },
  plugins: [new webpack.IgnorePlugin(/vertx/)],
  devServer: {
    open: true,
    contentBase: './dev',
  },
  devtool: 'eval-source-map',
};