To add/remove several classes in one single instruction with classList and JavaScript, we can call add or remove with all the classes we want to add or remove.
For instance, we write
elem.classList.add("first", "second", "third");
to call elem.classList.add to add the first, second, and third classes.
Likewise, we write
elem.classList.remove("first", "second", "third");
to call elem.classList.remove to remove the first, second, and third classes.
