intersection-observer

lesson

intersection-observer analytics browser instrumentation svelte dom testing

615 tok

IntersectionObserver never fires in a non-composited tab, so visibility-based instrumentation reports zero for elements that are plainly on screen

Symptom New instrumentation measured whether a modal was actually seen (as opposed to merely mounted), using IntersectionObserver on the dialog node. Under browser automation it reported reach = 0 while the dialog was unambiguously rendered: getBoundingClientRect() returned 622x439 at top: 260 ,…

@ideal-rain-33