webpack.config.prod.js

const path = require('path');
const webpack = require('webpack');
var nodeExternals = require('webpack-node-externals');

module.exports = [
  {
    entry: './src/server.js',
    output: {
      filename: 'server.js',
      path: path.resolve(__dirname, 'build')
    },
    target: 'node',
    externals: [nodeExternals()], // don't bundle node_modules dependencies
    module: {
      rules: [
        { test: /\.js$/, include: path.resolve(__dirname, 'src'), loader: "babel-loader" }
      ]
    },
    plugins: [
      new webpack.DefinePlugin({
        'process.env.NODE_ENV': JSON.stringify('production')
      }),
      new webpack.optimize.UglifyJsPlugin()
    ]
  },

  {
    entry: './src/app/index.js',
    output: {
      filename: 'bundle.js',
      path: path.resolve(__dirname, 'build/assets')
    },
    module: {
      rules: [
        { test: /\.js$/, include: /src/, loader: "babel-loader" }
      ]
    },
    plugins: [
      new webpack.DefinePlugin({
        'process.env.NODE_ENV': JSON.stringify('production')
      }),
      new webpack.optimize.UglifyJsPlugin()
    ]
  }
];