const webpack = require ('webpack'); const merge = require ('webpack-merge'); const UglifyJSPlugin = require ('uglifyjs-webpack-plugin'); const common = require ('./webpack.common.js'); module.exports = merge (common, { devtool: "source-map", plugins: [ new UglifyJSPlugin ({ sourceMap: true }), new webpack.DefinePlugin ({ 'process.env.NODE_ENV': JSON.stringify ('production') }) ] });