The entire book has been updated for React 0.14 and uses the latest version of JavaScript, ES6 (or ES2015). With this edition, readers get an expanded discussions of data flow, specifically around Flux, as well as discussions of using immutability with React, specifically around Immutable.js, and also the seamlessimmutable library. Throughout the book we reference bits of our example application, a reddit clone. Readers can read the full source code at http://git.io/vlcpa and view an online demo at http://git.io/vlCUI. This book also takes readers through four main topic areas to help them develop an edge with React: creating and composing components, tooling, working with React, and advanced topics including DOM manipulations, animations, performance tuning, and more. This book will enable readers to navigate all of these concepts and help you understand why they are beneficial and can help you build scalable Single Page Applications (SPAs).