One button photo gallery

for WarsawJS Workshop #26 but for everyone too!

The idea of this gallery is to make the whole code maximally simple and easy to understand. Deliberately there is only one file, so the whole code can be seen and understood by step-by-step development. I didn't use const because explaining it goes too much into detail and might be overwhelming for some beginner learners.

The half part of the 8 hour workshop we had was about developing this and it was more than enough. Might be actually a whole workshop only for this. Understanding this for beginners is really diffcult so if you have ideas how to skip the forEach loop or making the code even more simple let me know.

It would be helpful if you attached a list of all thigs to know to write such gallery.

Thank you for reading!