← You're polling setInterval to detect DOM changes. `MutationObserver` fires when they happen.Quiz
MutationObserver — DOM change detection
MutationObserver watches for changes to the DOM — child node additions/removals, attribute edits, and text content changes — and delivers them as a batch after each synchronous operation. These questions cover the observer's configuration options, what a MutationRecord contains, batching behavior, teardown, and how it compares to the setInterval polling pattern.
questions9
pass mark70%
resultsat the end
No account needed. Answer all 9 questions, then see your score with every answer explained and a reference to the spec or MDN — pass and you can claim a certificate.