MutationObserver: takeRecords() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The MutationObserver method
takeRecords() returns a list of all matching DOM changes
that have been detected but not yet processed by the observer's callback function,
leaving the mutation queue empty.
The most common use case for this is to immediately fetch all pending mutation records immediately prior to disconnecting the observer, so that any pending mutations can be processed when shutting down the observer.
Syntax
takeRecords()
Parameters
None.
Return value
An array of MutationRecord objects, each describing one change applied to
the observed portion of the document's DOM tree.
Note:
The queue of mutations which have occurred, but not been
delivered to the observer's callback is left empty after calling
takeRecords().
Examples
In this example, we demonstrate how to handle any undelivered
MutationRecords by calling takeRecords() just before
disconnecting the observer.
const targetNode = document.querySelector("#someElement");
const observerOptions = {
childList: true,
attributes: true,
};
const observer = new MutationObserver(callback);
observer.observe(targetNode, observerOptions);
/* later, when it's time to stop observing… */
/* handle any still-pending mutations */
let mutations = observer.takeRecords();
observer.disconnect();
if (mutations.length > 0) {
callback(mutations);
}
The code fetches any unprocessed mutation records, then invokes the
callback with the records so that they can be processed. This is done immediately prior
to calling disconnect() to stop observing
the DOM.
Specifications
| Specification |
|---|
| DOM # ref-for-dom-mutationobserver-takerecords① |
Browser compatibility
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takeRecords
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