This small tool will measure the boundaries (for instance width, height, top, left) of a view you reference. It is reactive and responds to changes in size, window-scroll and nested-area-scroll. Because there is no simple way to just get relative view coordinates. Yes, there is getBoundingClientRect, but it does not work when your content sits inside scroll areas whose offsets are simply neglected (as well as page scroll). Worse, mouse coordinates are relative to the viewport (the visible rect that contains the page). There is no easy way, for instance, to know that the mouse hovers over the upper/left corner of an element. This hook solves it for you.