Learn Babel (JavaScript compiler)!

Babel is a free and open-source JavaScript transcompiler that is mainly used to convert ECMAScript 2015+ (ES6+) code into a backwards compatible version of JavaScript that can be run by older JavaScript engines. Babel is a popular tool for using the newest features of the JavaScript programming language. Developers can use new JavaScript language features by using Babel to convert their source code into versions of JavaScript that evolving browsers are able to process. The core version of Babel is downloaded 5 million times a month as of 2016. Babel plugins are used to transform syntax that is not widely supported into a backwards-compatible version. For example, arrow functions, which are specified in ES6, are converted into regular function declarations. Non-standard JavaScript syntax such as JSX can also be transformed. Babel provides polyfills to provide support for features that are missing entirely from JavaScript environments. For example, static methods like Array.from and built-ins like Promise are only available in ES6+, but they can be used in older environments if a Babel polyfill is used. - read more on Wikipedia