webpack.config.js

const webpack = require('webpack');
const path = require('path');

module.exports = {
  devtool: 'source-map',
  entry: './src/index.js',
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        use: [
          'babel-loader',
          'eslint-loader'
        ]
      }
    ]
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': { NODE_ENV: '"production"' }
    }),
    new webpack.optimize.UglifyJsPlugin({
      sourceMap: true,
      compressor: {
        screw_ie8: true,
        drop_console: true,
        warnings: false
      }
    })
  ],
  externals: {
    react: {
      root: 'React',
      commonjs2: 'react',
      commonjs: 'react',
      amd: 'react'
    },
    'prop-types': {
      root: 'PropTypes',
      commonjs2: 'prop-types',
      commonjs: 'prop-types',
      amd: 'prop-types'
    },
    'react-router-dom': {
      root: 'ReactRouterDOM',
      commonjs2: 'react-router-dom',
      commonjs: 'react-router-dom',
      amd: 'react-router-dom'
    }
  },
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'react-breadcrumbs.min.js',
    library: 'react-breadcrumbs',
    libraryTarget: 'umd'
  }
}