elementclassListreplaceoldClassactive

The `classList.replace(oldClass, newClass)` method is a JavaScript DOM API method used to replace an existing class on an HTML element with a new one. It is a convenient way to manage the CSS classes applied to an element without having to manually remove the old class and then add the new one.

When `classList.replace()` is called on an element, it first checks if the `oldClass` exists. If it does, the `oldClass` is removed from the element's list of classes, and the `newClass` is added. If the `oldClass` does not exist on the element, the method does nothing, and no changes are made to the element's classes. The `newClass` is only added if the `oldClass` was successfully found and removed.

This method returns a boolean value. It returns `true` if the `oldClass` was found and replaced, and `false` if the `oldClass` was not found on the element.

An example of its usage would be `element.classList.replace('active', 'inactive');`. This would remove the class 'active' and add the class 'inactive' if 'active' was present on the element. This is particularly useful in dynamic user interfaces where styles need to be updated based on user interactions or application state. For instance, toggling between active and inactive states of a button or menu item. The `replace` method ensures that only one state class is applied at a time, preventing potential conflicts or unexpected styling.