Frontend Quiz App using Less for Css and Vanilla Javascript

What are you most proud of, and what would you do differently next time?

Somehow it was pretty tough for me to write it in vanilla js. I had to rewrite the js code thrice. The desire to leave it like this was strong but I kept it up. So not bad. Also this time work on Less and CSS and HTML went really smooth. And there is clear stable workflow for me now

What challenges did you encounter, and how did you overcome them?

I got so weird bugs in the process that couldn't find even theoretical explanation for them. For example when code reads the same data from an array, read 4 entries, but then for some reason cut them to 2. Inspite that while looping they still were 4. But I think I took many outcomes from this challenge. First of all, how frameworks ease us lives :-D. Second, if you don't have tools like redux and context, build code in the way that you needn't to pass data through many functions. Otherwise you'll get a lot of unexpected bugs. Clean eventListeners, otherwise it is a real pain, multiple calling events when you don't need it, memory leaks and so on. Keep functions independent as much as possible and don't forget about closures. Otherwise, you get unexpected results again. I know all that are known mistakes and reasons for existing best practices but somehow flew through fingers when writing in vanilla js.