Moving Codecademy to ECMAScript 6, Webpack, and React

When Codecademy was born in the summer of 2011, the natural choice for a frontend stack was Backbone + jQuery. Backbone was less than a year old and widely considered the state-of-the-art framework for creating frontend applications. Combined with jQuery, one could do a lot of novel things with the web browser. In our case, we built something that helped teach millions of people how to code, interactively, for free.