If you used a tutorial, what tutorial did you follow? (Please provide a link.)
https://www.codeproject.com/Articles/681130/Learn-JavaScript-Part-2-Space-Invaders

What did you learn?
That space invaders has nothing to do with people not following social distancing rules ;) Sorry, I couldn't resist. Seriously though, for the Space Invaders game in this collection I learned from the tutorial how to separate the game into different 'states', with each state being able to draw and update itself. With this design the main game loop is then just responsible for transitioning from one state to another, delegating user input to a state and running the drawing and update loops.