webpack.config.js

var path = require('path');
module.exports = {
  entry: './src/index.js',
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'index.js',
    libraryTarget: 'commonjs2'
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        include: path.resolve(__dirname, 'src'),
        exclude: /(node_modules|bower_components|build)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['env']
          }
        }
      },
      {
        test: /\.(eot|svg|otf|ttf|woff|woff2)$/,
        use: "file-loader"
      },
      {
        test: /\.(jpg|png|gif)$/,
        use: [
          "file-loader",
          {
            loader: "image-webpack-loader",
            options: {
              mozjpeg: {
                progressive: true
              },
              gifsicle: {
                interlaced: false
              },
              optipng: {
                optimizationLevel: 4
              },
              pngquant: {
                quality: "75-90",
                speed: 3
              }
            }
          }
        ]
      }
    ]
  },
  externals: {
    'react': 'commonjs react'
  }
};