Error?

Question

Why do I have this error?
https://code.sololearn.com/WcenB4Yq25Tu/?ref=app
Experts help

Answer 1

just remove '.' (dot) at postop and posdown (document.getElementsByClassName())and u good

Answer 2

check your getElementsByClassName arguments: some have a dot at start of the string... you must only provide the class name...

'.postop' should be used with querySelector/querySelectorAll...

Answer 3

Lily Mea thank u very much