Created
October 7, 2018 13:32
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| /* | |
| usage: scrollToElm($containerElement.get(0), $targetItem.get(0), 0.2); | |
| url: https://stackoverflow.com/a/51005649 | |
| */ | |
| function scrollToElm(container, elm, duration) { | |
| var pos = getRelativePos(elm); | |
| scrollTo(container, pos.top, duration); // duration in seconds | |
| } | |
| function getRelativePos(elm) { | |
| var pPos = elm.parentNode.getBoundingClientRect(), // parent pos | |
| cPos = elm.getBoundingClientRect(), // target pos | |
| pos = {}; | |
| pos.top = cPos.top - pPos.top + elm.parentNode.scrollTop; | |
| pos.right = cPos.right - pPos.right; | |
| pos.bottom = cPos.bottom - pPos.bottom; | |
| pos.left = cPos.left - pPos.left; | |
| return pos; | |
| } | |
| function scrollTo(element, to, duration, onDone) { | |
| var start = element.scrollTop, | |
| change = to - start, | |
| startTime = performance.now(), | |
| val, now, elapsed, t; | |
| function animateScroll() { | |
| now = performance.now(); | |
| elapsed = (now - startTime) / 1000; | |
| t = (elapsed / duration); | |
| element.scrollTop = start + change * easeInOutQuad(t); | |
| if (t < 1) | |
| window.requestAnimationFrame(animateScroll); | |
| else | |
| onDone && onDone(); | |
| }; | |
| animateScroll(); | |
| } | |
| function easeInOutQuad(t) { | |
| return t < .5 ? 2 * t * t : -1 + (4-2 * t) * t | |
| }; |
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