https://www.opapisa.it/wp-content/themes/opa-theme/js/jquery.sticky.js?ver=09f5e33f0ea83fd3685de15abb0236d4

1// Sticky Plugin
2// =============
3// Author: Anthony Garand
4// Improvements by German M. Bravo (Kronuz) and Ruud Kamphuis (ruudk)
5// Improvements by Leonardo C. Daronco (daronco)
6// Created: 2/14/2011
7// Date: 2/12/2012
8// Website: http://labs.anthonygarand.com/sticky
9// Description: Makes an element on the page stick on the screen as you scroll
10//              It will only set the 'top' and 'position' of your element, you
11//              might need to adjust the width in some cases.
12
13(function($) {
14    var defaults = {
15            topSpacing: 0,
16            bottomSpacing: 0,
17            className: 'is-sticky',
18            wrapperClassName: 'sticky-wrapper'
19        },
20        $window = $(window),
21        $document = $(document),
22        sticked = [],
23        windowHeight = $window.height(),
24        scroller = function() {
25            var scrollTop = $window.scrollTop(),
26                documentHeight = $document.height(),
27                dwh = documentHeight - windowHeight,
28                extra = (scrollTop > dwh) ? dwh - scrollTop : 0;
29            for (var i = 0; i < sticked.length; i++) {
30                var s = sticked[i],
31                    elementTop = s.stickyWrapper.offset().top,
32                    etse = elementTop - s.topSpacing - extra;
33                if (scrollTop <= etse) {
34                    if (s.currentTop !== null) {
35                        s.stickyElement
36                            .css('position', '')
37                            .css('top', '')
38                            .removeClass(s.className);
39                        s.stickyElement.parent().removeClass(s.className);
40                        s.currentTop = null;
41                    }
42                }
43                else {
44                    var newTop = documentHeight - s.stickyElement.outerHeight()
45                        - s.topSpacing - s.bottomSpacing - scrollTop - extra;
46                    if (newTop < 0) {
47                        newTop = newTop + s.topSpacing;
48                    } else {
49                        newTop = s.topSpacing;
50                    }
51                    if (s.currentTop != newTop) {
52                        s.stickyElement
53                            .css('position', 'fixed')
54                            .css('top', newTop)
55                            .addClass(s.className);
56                        s.stickyElement.parent().addClass(s.className);
57                        s.currentTop = newTop;
58                    }
59                }
60            }
61        },
62        resizer = function() {
63            windowHeight = $window.height();
64        },
65        methods = {
66            init: function(options) {
67                var o = $.extend(defaults, options);
68                return this.each(function() {
69                    var stickyElement = $(this);
70
71                    stickyId = stickyElement.attr('id');
72                    wrapper = $('<div></div>')
73                        .attr('id', stickyId + '-sticky-wrapper')
74                        .addClass(o.wrapperClassName);
75                    stickyElement.wrapAll(wrapper);
76                    var stickyWrapper = stickyElement.parent();
77                    stickyWrapper.css('height', stickyElement.outerHeight());
78                    sticked.push({
79                        topSpacing: o.topSpacing,
80                        bottomSpacing: o.bottomSpacing,
81                        stickyElement: stickyElement,
82                        currentTop: null,
83                        stickyWrapper: stickyWrapper,
84                        className: o.className
85                    });
86                });
87            },
88            update: scroller
89        };
90
91    // should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):
92    if (window.addEventListener) {
93        window.addEventListener('scroll', scroller, false);
94        window.addEventListener('resize', resizer, false);
95    } else if (window.attachEvent) {
96        window.attachEvent('onscroll', scroller);
97        window.attachEvent('onresize', resizer);
98    }
99
100    $.fn.sticky = function(method) {
101        if (methods[method]) {
102            return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
103        } else if (typeof method === 'object' || !method ) {
104            return methods.init.apply( this, arguments );
105        } else {
106            $.error('Method ' + method + ' does not exist on jQuery.sticky');
107        }
108    };
109    $(function() {
110        setTimeout(scroller, 0);
111    });

112})(jQuery);