MutationObserverInit.attributeOldValue
The MutationObserverInit dictionary's optional attributeOldValue property is used
to specify whether or not to record the prior value of the altered attribute in MutationRecord objects denoting attribute value changes.
Syntax
var options = {
attributeOldValue: true | false
}
Value
A Boolean value indicating whether or not the prior value of a changed attribute should
be included in the MutationObserver.oldValue property when reporting
attribute value changes. If true, oldValue is set accordingly.
If false, it is not.
When using attributeOldValue, setting the
attributes option to true
is optional.
Example
See MutationObserverInit.attributes for example code that sets this property.
Specifications
| Specification |
|---|
| DOM Standard (DOM) # ref-for-dom-mutationobserverinit-attributeoldvalueā |
Browser compatibility
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