The end of @babel/polyfill: The more efficient alternative?

The @babel/polyfill package allows you to emulate an ES6+ environment. Effectively, it ensures your ES6+ code is backwards compatible with older browsers and environments. It sounds like a golden fixture in modern JavaScript, right? Well, as of Babel 7.4.0, this powerful package had been deprecated. Composed of two dependent packages, core-js and regenerator-runtime, Babel now recommends installing them as dependencies and importing them at the top level of your application (think of index.js in a React app, for example).