First made using jquery, but trying to remake it with only javascript

Question

https://code.sololearn.com/WZkmy3jCpM9j

I built this with jquery and not I remade it with just javascript but I'm having problems
on lines 55 and 68.

Please help me understand where I went wrong?

Answer 1

try using window.onload

Answer 2

Like above, you need to load DOM before JS loads otherwise you will keep selecting elements that doesnt exist yet.

Answer 3

Here's a reference
https://www.sololearn.com/post/7444/?ref=app

Answer 4

says page not found when i click the link.