.......
if (!isProd) {
  config.devtool = 'cheap-module-eval-source-map';
  config.devServer.hot = true;
  config.devServer.host = '0.0.0.0';
  config.devServer.port = 80;
  config.devServer.watchOptions = {
    aggregateTimeout: 500,
    poll: true,
    ignored: /node_modules/,
  };
}
module.exports = config;

{
  mode: 'development',
  devServer: {
    host: '0.0.0.0',
    port: 80,
    contentBase: '/usr/src/app/build',
    stats: 'minimal',
    compress: true,
    historyApiFallback: true,
    hot: true,
    watchOptions: { aggregateTimeout: 500, poll: true, ignored: /node_modules/ }
  },
  entry: { app: './src/index.js' },
  output: {
    path: '/usr/src/app/build',
    publicPath: '/',
    filename: '[hash].js'
  },
  resolve: { extensions: [ '.js', '.jsx' ] },
  module: { rules: [ [Object], [Object], [Object], [Object] ] },
  performance: { hints: false },
  optimization: {
    minimize: false,
    minimizer: [ [TerserPlugin], [OptimizeCssAssetsWebpackPlugin] ],
    moduleIds: 'hashed',
    chunkIds: 'named',
    splitChunks: {
      chunks: 'all',
      minSize: 50000,
      maxSize: 250000,
      maxInitialRequests: 15,
      cacheGroups: [Object]
    }
  },
  plugins: [
    HtmlWebpackPlugin {
      options: [Object],
      childCompilerHash: undefined,
      assetJson: undefined,
      hash: undefined,
      version: 4
    },
    MiniCssExtractPlugin { options: [Object] },
    DefinePlugin { definitions: [Object] }
  ],
  devtool: 'cheap-module-eval-source-map'
}