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MutationObserver

The MutationObserver interface provides the ability to watch for changes being made to the DOM tree. It is designed as a replacement for the older Mutation Events feature, which was part of the DOM3 Events specification.

Constructor

MutationObserver()

Creates and returns a new MutationObserver which will invoke a specified callback function when DOM changes occur.

Instance methods

disconnect()

Stops the MutationObserver instance from receiving further notifications until and unless observe() is called again.

observe()

Configures the MutationObserver to begin receiving notifications through its callback function when DOM changes matching the given options occur.

takeRecords()

Removes all pending notifications from the MutationObserver's notification queue and returns them in a new Array of MutationRecord objects.

Mutation Observer & customize resize event listener & demo

Example

The following example was adapted from this blog post.

js

// Select the node that will be observed for mutations
const targetNode = document.getElementById("some-id");

// Options for the observer (which mutations to observe)
const config = { attributes: true, childList: true, subtree: true };

// Callback function to execute when mutations are observed
const callback = (mutationList, observer) => {
  for (const mutation of mutationList) {
    if (mutation.type === "childList") {
      console.log("A child node has been added or removed.");
    } else if (mutation.type === "attributes") {
      console.log(`The ${mutation.attributeName} attribute was modified.`);
    }
  }
};

// Create an observer instance linked to the callback function
const observer = new MutationObserver(callback);

// Start observing the target node for configured mutations
observer.observe(targetNode, config);

// Later, you can stop observing
observer.disconnect();

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
MutationObserver 2618 12 14 11 15 76 ≤374.4 2618 14 14 76 1.51.0
MutationObserver 2618 12 14 11 15 76 ≤374.4 2618 14 14 76 1.51.0
disconnect 18 12 14 11 15 6 4.4 18 14 14 6 1.0
observe
18Before Chrome 33, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Chrome throws a syntax error.
12Before Edge 79, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Edge throws a syntax error.
14Before Firefox 36, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Firefox throws a syntax error.
11Internet Explorer requires attributes: true when using attributeFilter or attributeOldValue. If attributes: true is not present, then Internet Explorer throws a syntax error.
15Before Opera 20, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Opera throws a syntax error.
6Before Safari 10.1, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Safari throws a syntax error.
4.4Before WebView 4.4.3, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then WebView throws a syntax error.
18Before Chrome 33, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Chrome throws a syntax error.
14Before Firefox 36, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Firefox throws a syntax error.
14Before Opera 20, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Opera throws a syntax error.
6Before Safari iOS 10.3, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Safari throws a syntax error.
1.0Before Samsung Internet 2.0, attributes: true is required when using attributeFilter or attributeOldValue. If attributes: true is not present, then Samsung Internet throws a syntax error.
takeRecords 20 12 14 11 15 6 4.4 25 14 14 6 1.5

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver