https://www.iso-ne.com/static-assets/js/jquery.sticky.js

1// Sticky Plugin v1.0.0 for jQuery
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      center: false,
20      getWidthFrom: ''
21    },
22    $window = $(window),
23    $document = $(document),
24    sticked = [],
25    windowHeight = $window.height(),
26    scroller = function() {
27      var scrollTop = $window.scrollTop(),
28        documentHeight = $document.height(),
29        dwh = documentHeight - windowHeight,
30        extra = (scrollTop > dwh) ? dwh - scrollTop : 0;
31
32      for (var i = 0; i < sticked.length; i++) {
33        var s = sticked[i],
34          elementTop = s.stickyWrapper.offset().top,
35          etse = elementTop - s.topSpacing - extra;
36
37        if (scrollTop <= etse) {
38          if (s.currentTop !== null) {
39            s.stickyElement
40              .css('position', '')
41              .css('top', '');
42            s.stickyElement.parent().removeClass(s.className);
43            s.currentTop = null;
44          }
45        }
46        else {
47          var newTop = documentHeight - s.stickyElement.outerHeight()
48            - s.topSpacing - s.bottomSpacing - scrollTop - extra;
49          if (newTop < 0) {
50            newTop = newTop + s.topSpacing;
51          } else {
52            newTop = s.topSpacing;
53          }
54          if (s.currentTop != newTop) {
55            s.stickyElement
56              .css('position', 'fixed')
57              .css('top', newTop);
58
59            if (typeof s.getWidthFrom !== 'undefined') {
60              s.stickyElement.css('width', $(s.getWidthFrom).width());
61            }
62
63            s.stickyElement.parent().addClass(s.className);
64            s.currentTop = newTop;
65          }
66        }
67      }
68    },
69    resizer = function() {
70      windowHeight = $window.height();
71    },
72    methods = {
73      init: function(options) {
74        var o = $.extend(defaults, options);
75        return this.each(function() {
76          var stickyElement = $(this);
77
78          var stickyId = stickyElement.attr('id');
79          var wrapper = $('<div></div>')
80            .attr('id', stickyId + '-sticky-wrapper')
81            .addClass(o.wrapperClassName);
82          stickyElement.wrapAll(wrapper);
83
84          if (o.center) {
85            stickyElement.parent().css({width:stickyElement.outerWidth(),marginLeft:"auto",marginRight:"auto"});
86          }
87
88          if (stickyElement.css("float") == "right") {
89            stickyElement.css({"float":"none"}).parent().css({"float":"right"});
90          }
91
92          var stickyWrapper = stickyElement.parent();
93          stickyWrapper.css('height', stickyElement.outerHeight());
94          sticked.push({
95            topSpacing: o.topSpacing,
96            bottomSpacing: o.bottomSpacing,
97            stickyElement: stickyElement,
98            currentTop: null,
99            stickyWrapper: stickyWrapper,
100            className: o.className,
101            getWidthFrom: o.getWidthFrom
102          });
103        });
104      },
105      update: scroller
106    };
107
108  // should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):
109  if (window.addEventListener) {
110    window.addEventListener('scroll', scroller, false);
111    window.addEventListener('resize', resizer, false);
112  } else if (window.attachEvent) {
113    window.attachEvent('onscroll', scroller);
114    window.attachEvent('onresize', resizer);
115  }
116
117  $.fn.sticky = function(method) {
118    if (methods[method]) {
119      return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
120    } else if (typeof method === 'object' || !method ) {
121      return methods.init.apply( this, arguments );
122    } else {
123      $.error('Method ' + method + ' does not exist on jQuery.sticky');
124    }
125  };
126  $(function() {
127    setTimeout(scroller, 0);
128  });
129})(jQuery);