Three.js is a cool library. It provides some 3D object rendering, animating, and hierarchy creation functionality that brings it to the level of industry-standard 3D game making studio programs (I think I don't need to give names here.) Although the library is good and functions well, structuring the project as code is pretty much given into the hands of the end developer. How assets are loaded (which I can't help criticizing - you need to copy module files from three.js examples AFAIK), how the scene is generated how all the animation mixers run in unison are given as problems to the developer.
I've seen pretty ingenius solutions to these problems, including using React to structure the app/game into components. Standardizing how the project is structured and works is important so in this document I'll list what solutions are needed so I can work on them before attempting the next big three.js projects.