v135 · dom / performance

Migration Wizard

Pick a deprecated Mutation Event and see the exact MutationObserver equivalent side-by-side, with a live demo that fires the MutationObserver version so you can verify the migration works in your browser.

checking mutation event status…

Chrome 135 removes the six deprecated Mutation Events: DOMSubtreeModified, DOMNodeInserted, DOMNodeRemoved, DOMNodeRemovedFromDocument, DOMNodeInsertedIntoDocument, and DOMCharacterDataModified. They caused severe performance degradation — every modification to the DOM triggered synchronous event dispatch across all listeners. MutationObserver batches notifications and is far more efficient.

Select a deprecated event

Side-by-side migration

Live demo — MutationObserver replacement

Target element

Initial content

Make a DOM change above to see MutationObserver fire…