We started the chapter by exploring the complementary library underscore-contrib and the alternative library lodash. We then discussed the Underscore functions that are similar with the ones standardized in the ES5 and ES6 specifications, and we focused on presenting some of the ES6 features that facilitate and simplify working with Underscore.

Writing code using ES6 syntax is key for becoming more productive in JavaScript, and we explored a couple of workflows based on Babel that enable most of the ES6 features today in the client and on the server. The next chapter will discuss how to automate JavaScript code-related tasks and how to reuse code between a client and server environments using both ES5 and ES6 focused approaches.