Better Code Style

[MaxEtMoritz]

"Code Style - What is that even?" make the code look like it is from one source and not like from 100 🤣

[MaxEtMoritz]

first step is done, i added ESLint Rules in the Test branch. They may not be optimized but better than nothing.

[MaxEtMoritz]

I have never learned JavaScript so i don't know good practices and how to code things that they are e.g. robust to errors.
If someone is good in JavaScript, please look over my Code and give feedback!