A colleague of mine insists that it is important to check first if a class exists on an element before adding or removing it.

Therefore he has lot of constructs in his code like this:

if (element.classList.contains('info')) {

    element.classList.remove('info');

}



if (!element.classList.contains('hint')) {

    element.classList.add('hint');

}

I personally guess that nothing would happen if one leaves the check with .contains( ) out.

Shall mean:

If the class isn't there nothing is removed. The statement is just meaningless.

If the class is already there then nothing is added.

Is my colleague right with his insisting on the check because not checking could result in some trouble?

Or can I forget about that checking?