webpack.config.js

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

let config = {
  entry: ['babel-polyfill', './src/client/index.jsx'],
  output: {
    path: path.resolve(__dirname, 'public'),
    filename: 'js/bundle.js'
  },
  module: {
    loaders: [
      { test: /\.css$/, loader: 'style-loader!css-loader' },
      // ...
    ],
    rules: [
      { test: /\.(js|jsx)$/, use: 'babel-loader', exclude: /node_modules/ },
      { test: /\.css$/,
        use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: 'css-loader',
          publicPath: '/public'
        })
      }
    ]
  },
  devtool: 'source-map',
  resolve: {
    extensions: ['.js', '.jsx']
  },
  devServer: {
    contentBase: path.join(__dirname, 'public'),
    compress: true,
    port: 3000,
    stats: 'minimal'
  },
  plugins: [
    new ExtractTextPlugin({
      filename: 'css/bundle.css',
      disable: false,
      allChunks: true
    }),
    new webpack.DefinePlugin({
      'process.env': {
        'NODE_ENV': JSON.stringify(process.env.NODE_ENV)
      }
    }),
  ]
};

module.exports = config;