Which statement accurately describes the behavior of the ‘IntersectionObserver’ API regarding element visibility?

Question

Web Development — Hard

Which statement accurately describes the behavior of the ‘IntersectionObserver’ API regarding element visibility?

Accepted Answer

IntersectionObserver is designed to be performant by running asynchronously outside the main thread's layout cycle. It avoids the performance pitfalls of scroll-based event listeners that trigger synchronous layout recalculations. Option A is incorrect because it does not trigger on layout changes. Option C is incorrect because it is event-driven, not polling-based. Option D is incorrect because it can observe intersections with any ancestor element, not just the viewport.