MutationEvent: prevValue property

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.

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 prevValue read-only property of the MutationEvent interface returns a string. In DOMAttrModified events, it represents the previous value of the Attr node. In DOMCharacterDataModified events, it contains the previous value of the CharacterData node. In all other cases, returns the empty string ("").

Value

A string.

Examples

js
element.addEventListener(
  "DOMAttrModified",
  (event) => {
    console.log(event.previousValue);
  },
  false,
);

Specifications

No specification found

No specification data found for api.MutationEvent.prevValue.
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Browser compatibility