webpack.config.js

const webpack = require('webpack');
const NODE_ENV = process.env.NODE_ENV || 'development';

const plugins = [
  new webpack.DefinePlugin({
    'process.env': {
      NODE_ENV: JSON.stringify(NODE_ENV),
    },
  }),
];

if (NODE_ENV === 'production') {
  plugins.push(new webpack.optimize.UglifyJsPlugin({
    compress: {
      warnings: false,
    },
    output: {
      comments: false,
    },
  }));
}

module.exports = {
  entry: './public/src/index.js',
  output: {
    path: './public/dist',
    filename: 'bundle.js',
  },
  module: {
    loaders: [
      {
        test: /\.js$|\.jsx$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        /*query: {
          presets: ['babel-preset-es2015', 'babel-preset-react'].map(require.resolve),
        },*/
      }, {
        test: /\.css$/,
        loader: 'style-loader!css-loader',
      },
    ],
  },
  plugins,
  resolve: {
    // you can now require('file') instead of require('file.js')
    extensions: ['', '.js', '.jsx', '.json'],
  },
  devtool: 'cheap-source-map',
};