How do you add multiple classes to an element in one operation?
classList.add() accepts multiple arguments, allowing you to add several classes in one operation using element.classList.add('class1', 'class2'). This is more efficient than multiple separate add() calls and cleaner than manipulating className directly. The method is variadic, meaning it can accept any number of arguments. If any of the classes already exist on the element, they are ignored without throwing an error.