Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
The MutationEvent interface provides event properties that are specific to modifications to the Document Object Model (DOM) hierarchy and nodes.
Adding DOM mutation listeners to a document profoundly degrades the performance of further DOM modifications to that document (making them 1.5 - 7 times slower!). Moreover, removing the listeners does not reverse the damage.
They have poor cross-browser compatibility: Safari doesn't support DOMAttrModified (see WebKit bug 8191) and Firefox doesn't support mutation name events (like DOMElementNameChanged and DOMAttributeNameChanged).
In DOMAttrModified events, contains the new value of the modified Attr node. In DOMCharacterDataModified events, contains the new value of the modified CharacterData node. In all other cases, returns the empty string ("").
In DOMAttrModified events, contains the previous value of the modified Attr node. In DOMCharacterDataModified events, contains previous new value of the modifiedCharacterData node. In all other cases, returns the empty string ("").