MutationEvent: attrChange property
Deprecated
To be removed
This feature is pending removal from browsers. Using it now may lead to broken functionality in future updates. Mutation events negatively impact performance and they were selected for removal from the web as part of Interop 2025.
Use the following features instead: MutationObserver.
Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.
The attrChange read-only property of the MutationEvent interface returns a number indicating what kind of change triggered the DOMAttrModified event. The three possible values are MODIFICATION (1), ADDITION (2) or REMOVAL (3). It has no meaning for other events and is then set to 0.
Value
An integer: 0, 1 (MODIFICATION), 2 (ADDITION), or 3 (REMOVAL).
Examples
element.addEventListener("DOMAttrModified", (event) => {
console.log(event.attrChange);
});