Check if an element is visible in a scrollable container
Written byPhuoc Nguyen
Category
Level 2 — Intermediate
Created
02 May, 2020
The following functions return
`true`
if the `ele`
element is visible in its scrollable container:const isVisible = function (ele, container) {
const eleTop = ele.offsetTop;
const eleBottom = eleTop + ele.clientHeight;
const containerTop = container.scrollTop;
const containerBottom = containerTop + container.clientHeight;
// The element is fully visible in the container
return (
(eleTop >= containerTop && eleBottom <= containerBottom) ||
// Some part of the element is visible in the container
(eleTop < containerTop && containerTop < eleBottom) ||
(eleTop < containerBottom && containerBottom < eleBottom)
);
};
We also can perform the check based on the bounding rectangles of both element and container:
const isVisible = function (ele, container) {
const { bottom, height, top } = ele.getBoundingClientRect();
const containerRect = container.getBoundingClientRect();
return top <= containerRect.top ? containerRect.top - top <= height : bottom - containerRect.bottom <= height;
};
#See also
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Phước Nguyễn