MutationObserver: The Modern Way to Watch and React to DOM Changes
Table of contents Introduction What is MutationObserver? Why MutationObserver replaced Mutation Events Core concepts and API surface Creating an observer The observe() options The MutationRecord object Controlling the observer (disconnect, takeRecords) Common use cases Performance considerations and best practices Practical examples Basic example: logging DOM changes Waiting for elements that don’t exist yet Observing attribute and text changes with oldValue Integration with frameworks / polyfills Pitfalls and gotchas When not to use MutationObserver Summary / Conclusion Introduction MutationObserver is the standardized, efficient browser API for watching changes in the DOM and reacting to them programmatically. It enables reliable detection of node additions/removals, attribute updates, and text changes without costly polling or deprecated Mutation Events. ...