E-commerce Product Page made with HTML, CSS, and JS

I am very new to JS so this is my hardest challenge yet. The "Cart" in this solution is a dummy one by the way. I still don't know how to effect a change in the DOM from JS for each run in a loop when using loops. The loop just executes to the end before attempting to interact with HTML. Any help or advice on this would be appreciated. Anyway, I would really love general feedback. And just maybe some thumbs up?