Improvements in ES6

The ECMAScript committee, which defines the specification for the JavaScript language itself, released a new specification called ECMAScript 6/ECMAScript 2015 in June 2015. The new standard, called ES6 for short, was a major revision of the JavaScript programming language and added a number of new paradigms intended to make development of JavaScript programs easier.

While ECMAScript defines the specification for the JavaScript language, the actual implementation of the language is dependent on the browser vendors and the maintainers of the various JavaScript engines. ES6 by itself is only a guideline, and because the browser vendors each have their own timeline for implementing new language features, the JavaScript language and the JavaScript implementations perged slightly. Features defined by ES6, such as classes, were not available in the major browsers, but developers wanted to use them anyway.

Enter Babel, the JavaScript transpiler. Babel can read and parse different JavaScript flavors (such as ES6, ES7, ES8, and React JSX) and convert it or compile it into browser-standard ES5. Even today, the entirety of ES6 has not yet been implemented by the browser vendors, so Babel remains an essential tool for developers wishing to write ES6 code.

The examples in this book will use ES6. If you're not yet familiar with the newer syntax, here are a few of the major features you'll see used throughout this book.