On the react site there is a demo on how to learn to think with react. This is the same tutorial executed using ES2015 and webpack as a build process. There are some gotcha's transforming your code to ES2015 whilst using React. In this demo there is a solution for these common challenges.
Follow the original and great tutorial here Es5 thinking in React and check the syntax differences using this project. Changelog found here
npm start
Check the app at http://localhost:8080