webpack.config.prod.js

const webpack = require('webpack');
const path = require('path');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  entry: ['babel-polyfill', './src/app.js'],
  output: {
    path: path.join(__dirname, 'public'),
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        loader: 'babel-loader',
        test: /\.js$|\.jsx$/,
        exclude: /node_modules/
      },
      {
        test: /\.css$/,
        use: [
          'style-loader',
          'css-loader',
        ]
      },
      {
        test: /\.scss$/,
        use: [
          'style-loader',
          'css-loader',
          'sass-loader',
        ]
      },
      {
        test: /\.(png|jpg|gif)$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 8192
            }
          }
        ]
      },
      {
        test: /\.(svg)$/,
        use: {
          loader: 'svg-url-loader',
          options: {}
        }
      }
    ]
  },
  plugins: [
    new UglifyJSPlugin({
      uglifyOptions: {
        parallel: true,
      },
    }),
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify('production')
    })
  ],
  // Dev tools are provided by webpack
  // Source maps help map errors to original react code
  // devtool: 'cheap-module-eval-source-map',

};