Help me to find the bug...

Question

Code is working fine in local browser but it's not working in Solo Learn
https://code.sololearn.com/WZu3GN9jyoRY/?ref=app

Answer 1

This is because the Javascript loads first in the JS Tab, meaning the HTML hasnt loaded yet, and can't get any elements from it.
This can be fixed by putting the variables inside a window.onload function.