Is there a smart Polyfill?

Question

JavaScript

It is necessary, depending on the version of the browser, to add something that is not there.
To make everything work on ES7 in the latest Chrome.
In an older version at the ES6 level.
And even older in ES5.
Option 2:
1) Connect 1 "smart".
2) Have multiple polyfills.
Question:
Which approach is better and what would you recommend?

Answer 1

Unfortunately, this does not happen. Polyfills only help to emulate some missing functionality. But the new syntax (arrow functions, declarations of variables through const, let, etc.) - alas, cannot be bypassed with a polyfill. You must first convert the code to ES5 when building the site. For this you need Babel.js