Retrieves the name of the attribute that was added, removed, or changed (or null otherwise).
This property is read-only.
ptr = object.attributeName
If the MutationRecord is of type attributes, you can use its attributeName property to identify the specific attribute that changed. If you registered (via the MutationObserver.observe method) to collect attributeOldValue data on your target node, the oldValue property provides the original attribute value before it was changed.