webpack.config.js

const webpack = require('webpack');

module.exports = {
  mode: process.env.NODE_ENV,
  devtool:
    process.env.NODE_ENV === 'development'
      ? 'eval-cheap-module-source-map'
      : false,

  entry: ['./client/index.jsx'],
  output: {
    filename: 'bundle.js',
  },
  devServer: {
    devMiddleware: {
      publicPath: '/ui/',
    },
    client: {
      logging: 'info',
    },
    proxy: {
      '/': `http://localhost:${4889}`,
    },
  },
  resolve: {
    extensions: ['.js', '.jsx'],
    alias: {
      'react-dom': '@hot-loader/react-dom',
    },
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': {
        NODE_ENV: JSON.stringify(process.env.NODE_ENV),
      },
    }),
  ].filter((p) => !!p),
  module: {
    rules: [
      {
        test: /\.css$/,
        use: ['style-loader', 'css-loader'],
      },
      {
        test: /\.m?js/,
        resolve: {
          fullySpecified: false,
        },
      },
      {
        test: /\.js(x?)$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
      },
    ],
  },
};