https://nashvillesongwritersfoundation.com/themes/user/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      responsiveWidth: false
22    },
23    $window = $(window),
24    $document = $(document),
25    sticked = [],
26    windowHeight = $window.height(),
27    scroller = function() {
28
29      var scrollTop = $window.scrollTop(),
30        documentHeight = $document.height(),
31        dwh = documentHeight - windowHeight,
32        extra = (scrollTop > dwh) ? dwh - scrollTop : 0;
33
34      for (var i = 0; i < sticked.length; i++) {
35        var s = sticked[i],
36          elementTop = s.stickyWrapper.offset().top,
37          etse = elementTop - s.topSpacing - extra;
38
39        if (scrollTop <= etse) {
40          if (s.currentTop !== null) {
41            s.stickyElement
42              .css('position', '')
43              .css('top', '');
44            s.stickyElement.trigger('sticky-end', [s]).parent().removeClass(s.className);
45            s.currentTop = null;
46
47            // var e = document.getElementById('nav_btt');
48            // if (e.style.display == 'block') e.style.display = 'none';
49            // else e.style.display = 'block';
50
51            // var ee = document.getElementById('navlogo');
52            // if (ee.style.display == 'inline-block') ee.style.display = 'none';
53            // else ee.style.display = 'inline-block';
54          }
55        }
56        else {
57          var newTop = documentHeight - s.stickyElement.outerHeight()
58            - s.topSpacing - s.bottomSpacing - scrollTop - extra;
59          if (newTop < 0) {
60            newTop = newTop + s.topSpacing;
61          } else {
62            newTop = s.topSpacing;
63          }
64          if (s.currentTop != newTop) {
65            s.stickyElement
66              .css('position', 'fixed')
67              .css('top', newTop);
68
69            if (typeof s.getWidthFrom !== 'undefined') {
70              s.stickyElement.css('width', $(s.getWidthFrom).width());
71            }
72
73            s.stickyElement.trigger('sticky-start', [s]).parent().addClass(s.className);
74            s.currentTop = newTop;
75            //var e = document.getElementById('nav_btt');
76            //if (e.style.display == 'block') e.style.display = 'none';
77            //else e.style.display = 'block';
78
79            //var ee = document.getElementById('navlogo');
80            //if (ee.style.display == 'inline-block') ee.style.display = 'none';
81            //else ee.style.display = 'inline-block';
82          }
83        }
84      }
85    },
86    resizer = function() {
87      windowHeight = $window.height();
88
89      for (var i = 0; i < sticked.length; i++) {
90        var s = sticked[i];
91        if (typeof s.getWidthFrom !== 'undefined' && s.responsiveWidth === true) {
92          s.stickyElement.css('width', $(s.getWidthFrom).width());
93        }
94      }
95    },
96    methods = {
97      init: function(options) {
98        var o = $.extend({}, defaults, options);
99        return this.each(function() {
100          var stickyElement = $(this);
101
102          var stickyId = stickyElement.attr('id');
103          var wrapperId = stickyId ? stickyId + '-' + defaults.wrapperClassName : defaults.wrapperClassName 
104          var wrapper = $('<div></div>')
105            .attr('id', stickyId + '-sticky-wrapper')
106            .addClass(o.wrapperClassName);
107          stickyElement.wrapAll(wrapper);
108
109          if (o.center) {
110            stickyElement.parent().css({width:stickyElement.outerWidth(),marginLeft:"auto",marginRight:"auto"});
111          }
112
113          if (stickyElement.css("float") == "right") {
114            stickyElement.css({"float":"none"}).parent().css({"float":"right"});
115          }
116
117          var stickyWrapper = stickyElement.parent();
118          stickyWrapper.css('height', stickyElement.outerHeight());
119          sticked.push({
120            topSpacing: o.topSpacing,
121            bottomSpacing: o.bottomSpacing,
122            stickyElement: stickyElement,
123            currentTop: null,
124            stickyWrapper: stickyWrapper,
125            className: o.className,
126            getWidthFrom: o.getWidthFrom,
127            responsiveWidth: o.responsiveWidth
128          });
129        });
130      },
131      update: scroller,
132      unstick: function(options) {
133        return this.each(function() {
134          var unstickyElement = $(this);
135
136          var removeIdx = -1;
137          for (var i = 0; i < sticked.length; i++)
138          {
139            if (sticked[i].stickyElement.get(0) == unstickyElement.get(0))
140            {
141                removeIdx = i;
142            }
143          }
144          if(removeIdx != -1)
145          {
146            sticked.splice(removeIdx,1);
147            unstickyElement.unwrap();
148            unstickyElement.removeAttr('style');
149          }
150        });
151      }
152    };
153
154  // should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):
155  if (window.addEventListener) {
156    window.addEventListener('scroll', scroller, false);
157    window.addEventListener('resize', resizer, false);
158  } else if (window.attachEvent) {
159    window.attachEvent('onscroll', scroller);
160    window.attachEvent('onresize', resizer);
161  }
162
163  $.fn.sticky = function(method) {
164    if (methods[method]) {
165      return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
166    } else if (typeof method === 'object' || !method ) {
167      return methods.init.apply( this, arguments );
168    } else {
169      $.error('Method ' + method + ' does not exist on jQuery.sticky');
170    }
171  };
172
173  $.fn.unstick = function(method) {
174    if (methods[method]) {
175      return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
176    } else if (typeof method === 'object' || !method ) {
177      return methods.unstick.apply( this, arguments );
178    } else {
179      $.error('Method ' + method + ' does not exist on jQuery.sticky');
180    }
181
182  };
183  $(function() {
184    setTimeout(scroller, 0);
185  });
186})(jQuery);