Webpack 4 comes with the following statement:
webpack.optimize.UglifyJsPlugin has been removed, please use config.optimization.minimize instead. <
webpack.optimize.UglifyJsPlugin has been removed, please use config.optimization.minimize instead.
Without adding uglifyjs-webpack-plugin, you can just add this to the end of your webpack.prod.config.js file:
uglifyjs-webpack-plugin
optimization: { minimize: false }