https://thegreekfest.com/dev/js/tmstickup.js

1(function($,undefined){
2	var 
3		def={
4			stuckClass:'isStuck'			
5		}
6		,doc=$(document)
7
8	$.fn.TMStickUp=function(opt){
9		opt=$.extend(true,{},def,opt)
10
11		$(this).each(function(){
12			var $this=$(this)
13				,posY//=$this.offset().top+$this.outerHeight()
14				,isStuck=false
15				,clone=$this.clone().appendTo($this.parent()).addClass(opt.stuckClass)
16				,height//=$this.outerHeight()
17				,stuckedHeight=clone.outerHeight()
18				,opened//=$.cookie&&$.cookie('panel1')==='opened'
19				,tmr
20
21			$(window).resize(function(){
22				clearTimeout(tmr)				
23				clone.css({top:isStuck?0:-stuckedHeight,visibility:isStuck?'visible':'hidden'})
24				tmr=setTimeout(function(){
25					posY=$this.offset().top//+$this.outerHeight()				
26					height=$this.outerHeight()
27					stuckedHeight=clone.outerHeight()
28					opened=$.cookie&&$.cookie('panel1')==='opened'
29
30					clone.css({top:isStuck?0:-stuckedHeight})
31				},40)
32			}).resize()
33
34			clone.css({
35				position:'fixed'				
36				,width:'100%'
37			})
38
39			$this
40				.on('rePosition',function(e,d){
41					if(isStuck)
42						clone.animate({marginTop:d},{easing:'linear'})
43					if(d===0)
44						opened=false
45					else
46						opened=true
47				})
48			
49			doc
50				.on('scroll',function(){
51					var scrollTop=doc.scrollTop()
52
53					if(scrollTop>=posY&&!isStuck){						
54						clone
55							.stop()
56							.css({visibility:'visible'})
57							.animate({
58								top:0
59								,marginTop:opened?50:0
60							},{
61
62							})
63							
64						isStuck=true
65					}
66					
67					if(scrollTop<posY+height&&isStuck){
68                        $('.js-search').removeClass('active');
69						clone
70							.stop()
71							.animate({
72								top:-stuckedHeight
73								,marginTop:0
74							},{
75								duration:200
76								,complete:function(){
77									clone.css({visibility:'hidden'})
78								}
79							})
80						
81						isStuck=false
82					}			
83				})				
84				.trigger('scroll')
85		})
86	}
87})(jQuery)