I tried any JS code - TypeError, another one - again Error!

Question

https://cdn.discordapp.com/attachments/1101905487076802701/1124387929104584784/Screenshot_727.png
https://cdn.discordapp.com/attachments/1101905487076802701/1124387929356238908/Screenshot_726.png
https://cdn.discordapp.com/attachments/1101905487076802701/1124387929612111942/Screenshot_725.png

for code: https://www.sololearn.com/compiler-playground/WdTGP4Lp8DV1

Answer 1

You can only get the element by id once the DOM is fully loaded.

Put the part inside of the onload function.

Answer 2

山 Zed Please send the code not images of it.

Answer 3

As already mentioned:

Put
let btn = document.getElementById("favorite-button-littleone-berryassort")
inside the onload function.

Answer 4

Junior, here it is.

https://www.sololearn.com/compiler-playground/WdTGP4Lp8DV1