webpack.config.js

const webpack = require('webpack');
const pkg = require('./package.json');

const env = process.env.NODE_ENV;
const config = {
  resolve: {
    extensions: ['.js', '.jsx'],
    modules: ['src', 'node_modules']
  },
  output: {
    library: pkg.name,
    libraryTarget: 'umd'
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        options: {
          cacheDirectory: true
        }
      }
    ]
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify(env)
    })
  ],
  externals: {
    // Don't package React with the component.
    react: 'react',
    'react-dom': 'react-dom',
    'redux-form': 'redux-form',
    'react-redux': 'react-redux'
    // If your component depends on external utility libraries like lodash,
    // you might want to add them here.
    // Refer to https://webpack.js.org/configuration/externals/ for more info.
  }
};

if (env === 'production') {
  config.plugins.push(
    new webpack.optimize.UglifyJsPlugin({
      sourceMap: true,
      beautify: false,
      comments: false,
      compress: {
        drop_console: true
      },
      mangle: {
        screw_ie8: true,
        keep_fnames: true
      }
    })
  );
}

module.exports = config;