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- export default (destination, duration = 200, easing = 'linear', callback) => {
- const easings = {
- linear(t) {
- return t;
- },
- easeInQuad(t) {
- return t * t;
- },
- easeOutQuad(t) {
- return t * (2 - t);
- },
- easeInOutQuad(t) {
- return t < 0.5 ? 2 * t * t : -1 + (4 - 2 * t) * t;
- },
- easeInCubic(t) {
- return t * t * t;
- },
- easeOutCubic(t) {
- return (--t) * t * t + 1;
- },
- easeInOutCubic(t) {
- return t < 0.5 ? 4 * t * t * t : (t - 1) * (2 * t - 2) * (2 * t - 2) + 1;
- },
- easeInQuart(t) {
- return t * t * t * t;
- },
- easeOutQuart(t) {
- return 1 - (--t) * t * t * t;
- },
- easeInOutQuart(t) {
- return t < 0.5 ? 8 * t * t * t * t : 1 - 8 * (--t) * t * t * t;
- },
- easeInQuint(t) {
- return t * t * t * t * t;
- },
- easeOutQuint(t) {
- return 1 + (--t) * t * t * t * t;
- },
- easeInOutQuint(t) {
- return t < 0.5 ? 16 * t * t * t * t * t : 1 + 16 * (--t) * t * t * t * t;
- }
- };
- const start = window.pageYOffset;
- const startTime = 'now' in window.performance ? performance.now() : new Date().getTime();
- const documentHeight = Math.max(document.body.scrollHeight, document.body.offsetHeight, document.documentElement.clientHeight, document.documentElement.scrollHeight, document.documentElement.offsetHeight);
- const windowHeight = window.innerHeight || document.documentElement.clientHeight || document.getElementsByTagName('body')[0].clientHeight;
- const destinationOffset = typeof destination === 'number' ? destination : destination.offsetTop;
- const destinationOffsetToScroll = Math.round(documentHeight - destinationOffset < windowHeight ? documentHeight - windowHeight : destinationOffset);
- if ('requestAnimationFrame' in window === false) {
- window.scroll(0, destinationOffsetToScroll);
- if (callback) {
- callback();
- }
- return;
- }
- function scroll() {
- const now = 'now' in window.performance ? performance.now() : new Date().getTime();
- const time = Math.min(1, ((now - startTime) / duration));
- const timeFunction = easings[easing](time);
- window.scroll(0, Math.ceil((timeFunction * (destinationOffsetToScroll - start)) + start));
- if (window.pageYOffset === destinationOffsetToScroll) {
- if (callback) {
- callback();
- }
- return;
- }
- requestAnimationFrame(scroll);
- }
- scroll();
- }
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