MutationObserver.takeRecords

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 stopping down the observer.

Syntax

mutationRecords = mutationObserver.takeRecords()

Parameters

None.

Return value

An array MutationRecord objects, each describing one change applied to the portion of the document's DOM tree.

Example

In this example, we demonstrate how to handle any undelivered MutationRecords by calling takeRecords() just before disconnecting the observer.

var targetNode = document.querySelector("#someElement");
var observerOptions = {
  childList: true,
  attributes: true
}

var observer = new MutationObserver(callback);
observer.observe(targetNode, observerOptions);

/* ...later, when it's time to stop observing... */

/* handle any still-pending mutations */

var mutations = observer.takeRecords();

if (mutations) {
  callback(mutations);
}

observer.disconnect();

The code in lines 12-17 fetches any unprocessed mutation records and invokes the callback with that list of records so that they can be processed. This is done immediately prior to calling disconnect() to stop observing the DOM.

Specifications

Browser compatibilityUpdate compatibility data on GitHub