I am working on a pet project to build a slot machine. I'm looking at it from a regulatory angle as well. As such, I want to understand the code as much as poss

I am working on a pet project to build a slot machine. I'm looking at it from a regulatory angle as well. As such, I want to understand the code as much as possible. I did some initial tests in Node. When I installed express, for routing, it added tens of dependencies and 2.5MB of code files. They call it "minimal". No thanks. I'll skip the router, for now or write my own.