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.

Note: The queue of mutations which have occurred but not been delivered to your callback is left empty after calling takeRecords().

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

Specification Status Comment
DOM
The definition of 'MutationObserver.takeRecords()' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support18 Yes1411156
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support1818 Yes14146 Yes

Document Tags and Contributors

Contributors to this page: fscholz, Sheppy
Last updated by: fscholz,