This implementation is done using webpack. Every folder has it's own attached readme.md file that explains the project and it's implementation. You will find explanantion in there which will explain certain theories behind some classes of Three.js.
At the time of upload npm version used was 6.14.13 & node version used was 14.7.1 while this might be true for almost all projects in this repositories but i might update them in future projects.
I will make a repository on the implementation of Three.js with React separately in the future using React Three Fiber.