E-commerce product page

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

I am the most proud that it actually works and looks decent

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

It was not and still is not obvious for me how is this thing with slider supposed to be done. Should I have just one? Or is it better to make two of them and replace one with another? How people do things like that? Is there a right way?

Another one concerns the cart. How are things like that done without backend? So i just did what I thought was right. It works, but i would gladly use some advice

What specific areas of your project would you like help with?

Js in this project looks terrible and i know that things are not done this way. I would love to see different examples of how other people approach things like this