(function($) {
var defaults = {
topSpacing: 0,
bottomSpacing: 0,
className: 'is-sticky',
wrapperClassName: 'sticky-wrapper',
center: false,
getWidthFrom: ''
},
$window = $(window),
$document = $(document),
sticked = [],
windowHeight = $window.height(),
scroller = function() {
var scrollTop = $window.scrollTop(),
documentHeight = $document.height(),
dwh = documentHeight - windowHeight,
extra = (scrollTop > dwh) ? dwh - scrollTop : 0;
for (var i = 0; i < sticked.length; i++) {
var s = sticked[i],
elementTop = s.stickyWrapper.offset().top,
etse = elementTop - s.topSpacing - extra;
if (scrollTop <= etse) {
if (s.currentTop !== null) {
s.stickyElement
.css('position', '')
.css('top', '');
s.stickyElement.parent().removeClass(s.className);
s.currentTop = null;
}
}
else {
var newTop = documentHeight - s.stickyElement.outerHeight()
- s.topSpacing - s.bottomSpacing - scrollTop - extra;
if (newTop < 0) {
newTop = newTop + s.topSpacing;
} else {
newTop = s.topSpacing;
}
if (s.currentTop != newTop) {
s.stickyElement
.css('position', 'fixed')
.css('top', newTop);
if (typeof s.getWidthFrom !== 'undefined') {
s.stickyElement.css('width', $(s.getWidthFrom).width());
}
s.stickyElement.parent().addClass(s.className);
s.currentTop = newTop;
}
}
}
},
resizer = function() {
windowHeight = $window.height();
},
methods = {
init: function(options) {
var o = $.extend({}, defaults, options);
return this.each(function() {
var stickyElement = $(this);
var stickyId = stickyElement.attr('id');
var wrapperId = stickyId ? stickyId + '-' + defaults.wrapperClassName : defaults.wrapperClassName
var wrapper = $('<div></div>')
.attr('id', stickyId + '-sticky-wrapper')
.addClass(o.wrapperClassName);
stickyElement.wrapAll(wrapper);
if (o.center) {
stickyElement.parent().css({width:stickyElement.outerWidth(),marginLeft:"auto",marginRight:"auto"});
}
if (stickyElement.css("float") == "right") {
stickyElement.css({"float":"none"}).parent().css({"float":"right"});
}
var stickyWrapper = stickyElement.parent();
stickyWrapper.css('height', stickyElement.outerHeight());
sticked.push({
topSpacing: o.topSpacing,
bottomSpacing: o.bottomSpacing,
stickyElement: stickyElement,
currentTop: null,
stickyWrapper: stickyWrapper,
className: o.className,
getWidthFrom: o.getWidthFrom
});
});
},
update: scroller,
unstick: function(options) {
return this.each(function() {
var unstickyElement = $(this);
var removeIdx = -1;
for (var i = 0; i < sticked.length; i++)
{
if (sticked[i].stickyElement.get(0) == unstickyElement.get(0))
{
removeIdx = i;
}
}
if(removeIdx != -1)
{
sticked.splice(removeIdx,1);
unstickyElement.unwrap();
unstickyElement.removeAttr('style');
}
});
}
};
// should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):
if (window.addEventListener) {
window.addEventListener('scroll', scroller, false);
window.addEventListener('resize', resizer, false);
} else if (window.attachEvent) {
window.attachEvent('onscroll', scroller);
window.attachEvent('onresize', resizer);
}
$.fn.sticky = function(method) {
if (methods[method]) {
return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
} else if (typeof method === 'object' || !method ) {
return methods.init.apply( this, arguments );
} else {
$.error('Method ' + method + ' does not exist on jQuery.sticky');
}
};
$.fn.unstick = function(method) {
if (methods[method]) {
return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
} else if (typeof method === 'object' || !method ) {
return methods.unstick.apply( this, arguments );
} else {
$.error('Method ' + method + ' does not exist on jQuery.sticky');
}
};
$(function() {
setTimeout(scroller, 0);
});
})(jQuery);