javascript – Rewrite the half-finished game in ES6 and Phaser3?

I wrote a game a few years ago that requires work. At the time, I was just starting to unplug and so I have a single file of about 3,000 lines of javascript code es5, with the help of Phaser Community Edition 2.7.

During the last year, I wrote React and I use the NPM system. So, of course, I want to rewrite the game using es6, linting, live refresh, etc. Is there a guide for organizing a Phaser game (or a video game) regarding the file structure?

Tell me it's best to continue working on Phaser CE if switching to Phaser 3 will not help much. In addition, I used Cocoon.io and I see that they have closed their shop. Is there a good alternative or is it another obstacle? Thank you.