var path = require('path'); module.exports = { entry: './src/index.js', output: { path: path.resolve(__dirname, 'build'), filename: 'index.js', libraryTarget: 'commonjs2' // THIS IS THE MOST IMPORTANT LINE! :mindblow: I wasted more than 2 days until realize this was the line most important in all this guide. }, module: { rules: [ { test: /\.js$/, include: path.resolve(__dirname, 'src'), exclude: /(node_modules|bower_components|build)/, use: { loader: 'babel-loader', options: { presets: ['env'] } } } ] }, externals: { 'react': 'commonjs react' // this line is just to use the React dependency of our parent-testing-project instead of using our own React. } };