https://cross-border-magazine.com/wp-content/plugins/oxy-toolbox/modules/back-to-top/js/script.js?ver=1.6.2

1// Credit: https://codyhouse.co/gem/back-to-top/
2// License: https://codyhouse.co/mit
3// Details: https://codyhouse.co/license#experiments
4
5// Utility function
6function Util () {};
7
8/* 
9	class manipulation functions
10*/
11Util.hasClass = function(el, className) {
12	if (el.classList) return el.classList.contains(className);
13	else return !!el.className.match(new RegExp('(\\s|^)' + className + '(\\s|$)'));
14};
15
16Util.addClass = function(el, className) {
17	var classList = className.split(' ');
18 	if (el.classList) el.classList.add(classList[0]);
19 	else if (!Util.hasClass(el, classList[0])) el.className += " " + classList[0];
20 	if (classList.length > 1) Util.addClass(el, classList.slice(1).join(' '));
21};
22
23Util.removeClass = function(el, className) {
24	var classList = className.split(' ');
25	if (el.classList) el.classList.remove(classList[0]);	
26	else if(Util.hasClass(el, classList[0])) {
27		var reg = new RegExp('(\\s|^)' + classList[0] + '(\\s|$)');
28		el.className=el.className.replace(reg, ' ');
29	}
30	if (classList.length > 1) Util.removeClass(el, classList.slice(1).join(' '));
31};
32
33/* 
34	Smooth Scroll
35*/
36
37Util.scrollTo = function(final, duration, cb, scrollEl) {
38  var element = scrollEl || window;
39  var start = element.scrollTop || document.documentElement.scrollTop,
40    currentTime = null;
41
42  if(!scrollEl) start = window.scrollY || document.documentElement.scrollTop;
43      
44  var animateScroll = function(timestamp){
45  	if (!currentTime) currentTime = timestamp;        
46    var progress = timestamp - currentTime;
47    if(progress > duration) progress = duration;
48    var val = Math.easeInOutQuad(progress, start, final-start, duration);
49    element.scrollTo(0, val);
50    if(progress < duration) {
51        window.requestAnimationFrame(animateScroll);
52    } else {
53      cb && cb();
54    }
55  };
56
57  window.requestAnimationFrame(animateScroll);
58};
59
60/* 
61	Animation curves
62*/
63Math.easeInOutQuad = function (t, b, c, d) {
64	t /= d/2;
65	if (t < 1) return c/2*t*t + b;
66	t--;
67	return -c/2 * (t*(t-2) - 1) + b;
68};
69
70(function(){
71	jQuery(document).ready(() => {
72	    // Back to Top - by CodyHouse.co
73		var backTop = document.getElementsByClassName('js-cd-top')[0],
74			offset = 300, // browser window scroll (in pixels) after which the "back to top" link is shown
75			offsetOpacity = 1200, //browser window scroll (in pixels) after which the "back to top" link opacity is reduced
76			scrollDuration = 700,
77			scrolling = false;
78		if( backTop ) {
79			//update back to top visibility on scrolling
80			window.addEventListener("scroll", function(event) {
81				if( !scrolling ) {
82					scrolling = true;
83					(!window.requestAnimationFrame) ? setTimeout(checkBackToTop, 250) : window.requestAnimationFrame(checkBackToTop);
84				}
85			});
86
87			//smooth scroll to top
88			backTop.addEventListener('click', function(event) {
89				event.preventDefault();
90				(!window.requestAnimationFrame) ? window.scrollTo(0, 0) : Util.scrollTo(0, scrollDuration);
91			});
92		}
93
94		function checkBackToTop() {
95			var windowTop = window.scrollY || document.documentElement.scrollTop;
96			( windowTop > offset ) ? Util.addClass(backTop, 'cd-top--is-visible') : Util.removeClass(backTop, 'cd-top--is-visible cd-top--fade-out');
97			( windowTop > offsetOpacity ) && Util.addClass(backTop, 'cd-top--fade-out');
98			scrolling = false;
99		}
100	});
101
102	
103})();