https://www.sbts.edu/wp-content/plugins/popupbuilder-scroll/public/js/Scroll.js?ver=4.2.7

1SgpbEventListener.prototype.sgpbOnScroll = function(listenerObj, eventData)
2{
3	var scrollValue = eventData['value'];
4	var operator = eventData['operator'];
5
6	if (operator == 'scrollDistance') {
7		var scrollIntValue = parseInt(scrollValue);
8		var showAfter = scrollIntValue;
9		var docHeight = jQuery(document).height();
10		var winHeight = jQuery(window).height();
11
12		var height = (docHeight - winHeight);
13		if (scrollValue.indexOf('%') != '-1') {
14			showAfter = (height*scrollIntValue)/100;
15		}
16		if (scrollValue.indexOf('em') != '-1') {
17			scrollIntValue = parseFloat(eventData['value']);
18			var bodyFontSize = jQuery("body").css('font-size');
19			showAfter = parseInt(bodyFontSize)*scrollIntValue;
20		}
21		if (scrollValue.indexOf('rem') != '-1') {
22			scrollIntValue = parseFloat(eventData['value']);
23			var constOfRem = 16;
24			showAfter = parseInt(constOfRem)*scrollIntValue;
25		}
26	}
27	else if (operator == 'scrollTop') {
28		var lastScrollTop = 0;
29		window.addEventListener('scroll', function() {
30		   var currentStatement = window.pageYOffset || document.documentElement.scrollTop;
31		   if (currentStatement < lastScrollTop) {
32			  if (currentStatement == 0) {
33			  	listenerObj.getPopupObj().prepareOpen();
34			  }
35		   }
36		   lastScrollTop = currentStatement <= 0 ? 0 : currentStatement;
37		}, false);
38	}
39	else {
40		showAfter = 0;
41		var element = jQuery(eventData['value']);
42		var elementPosition = element.position();
43		var elementHeight = element.height();
44		if (elementPosition && elementPosition.top) {
45			showAfter = elementPosition.top;
46		}
47		/* open popup when the specified target is in the middle of the window */
48		showAfter = showAfter+(elementHeight/2);
49	}
50
51	var scrollStatus = false;
52	var alreadyOpened = false;
53	var windowHeight = jQuery(window).height();
54	jQuery(window).on('scroll touchmove', function() {
55		setTimeout(function() {
56			var scrollTop = jQuery(window).scrollTop();
57			var scrollTopWithHeight = scrollTop + windowHeight/2;
58			if (!alreadyOpened && (scrollTop <= showAfter && scrollTopWithHeight >= showAfter)) {
59				if (scrollStatus == false) {
60					listenerObj.getPopupObj().prepareOpen();
61					scrollStatus = true;
62					alreadyOpened = true;
63				}
64			}
65			/* if the value smaller than the window height, it should be opened on any scroll */
66			if ((windowHeight > showAfter) && !alreadyOpened) {
67				listenerObj.getPopupObj().prepareOpen();
68				scrollStatus = true;
69				alreadyOpened = true;
70			}
71		}, 100);
72	});
73};