Introduction

Babel is a generic multi-purpose compiler for JavaScript. Using Babel you can use (and create) the next generation of JavaScript, as well as the next generation of JavaScript tooling.

JavaScript as a language is constantly evolving, with new specs and proposals coming out with new features all the time. Using Babel will allow you to use many of these features years before they are available everywhere.

Babel does this by compiling down JavaScript code written with the latest standards into a version that will work everywhere today. This process is known as source-to-source compiling, also known as transpiling.

For example, Babel could transform the new ES2015 arrow function syntax from this:

const square = n => n * n;

Into the following:

const square = function square(n) {
  return n * n;
};

However, Babel can do much more than this as Babel has support for syntax extensions such as the JSX syntax for React and Flow syntax support for static type checking.

Further than that, everything in Babel is simply a plugin and anyone can go out and create their own plugins using the full power of Babel to do whatever they want.

Even further than that, Babel is broken down into a number of core modules that anyone can use to build the next generation of JavaScript tooling.

Many people do too, the ecosystem that has sprung up around Babel is massive and very diverse. Throughout this handbook I’ll be covering both how built-in Babel tools work as well as some useful things from around the community.