webpack.config.js

const path = require('path');
const ExtractTextPlugin = require("extract-text-webpack-plugin");
const webpack = require('webpack');
const merge = require('webpack-merge');

// common config across dev and prod setups
const common = {
  entry: path.join(__dirname, 'client'),
  output: {
    path: path.join(__dirname, 'server', 'public'),
    filename: 'bundle.js'
  },

  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        loader: 'babel',
        query: {
          presets: ["es2015", "react"]
        }
      },

      { 
        test: /\.json$/,
        loader: 'json-loader'
      },

      {
        test: /\.css$/,
        loader: ExtractTextPlugin.extract("style-loader", "css-loader")
      },
      
      { 
        test: /\.png$/,
        loader: "file-loader"
      }
    ]
  },

  plugins: [
    new ExtractTextPlugin('styles.css')
  ]
};

// config for a dev setup
const devConfig = {
  devtool: 'source-maps',
  devServer: {
    inline: true,
    hot: true,
    historyApiFallback: true
  }
};

const prodConfig = {
  devtool: 'source-maps',
  // plugins: [
  //   new webpack.optimize.UglifyJsPlugin({
  //     beautify: false,
  //     comments: false,
  //     compress: {
  //       warnings: false,
  //     },
  //     mangle: {
  //       except: ['$'],
  //       screw_ie8: true,
  //       keep_fnames: true
  //     }
  //   })
  // ]
};

// export config for prod or dev based on npm 
// command ran
// npm run dev would do development build
// npm run build would do production build
const target = process.env.npm_lifecycle_event;
switch (target) {
  case 'dev' :
    module.exports = merge(common, devConfig);
    break;
  default :
    module.exports = merge(common, prodConfig);
    break;
}