https://www.missionlocale-aurillac.fr/js/cdtop/cdtop.js

1jQuery(document).ready(function($){
2	
3	if(!$(".cd-top").exists())
4		$("body").append('<a href="#0" class="cd-top"></a>');
5	
6	// browser window scroll (in pixels) after which the "back to top" link is shown
7	var offset = 300,
8		//browser window scroll (in pixels) after which the "back to top" link opacity is reduced
9		offset_opacity = 1200,
10		//duration of the top scrolling animation (in ms)
11		scroll_top_duration = 700,
12		//grab the "back to top" link
13		$back_to_top = $('.cd-top');
14
15	//hide or show the "back to top" link
16	$(window).scroll(function(){
17		( $(this).scrollTop() > offset ) ? $back_to_top.addClass('cd-is-visible') : $back_to_top.removeClass('cd-is-visible cd-fade-out');
18		if( $(this).scrollTop() > offset_opacity ) { 
19			$back_to_top.addClass('cd-fade-out');
20		}
21	});
22
23	//smooth scroll to top
24	$back_to_top.on('click', function(event){
25		event.preventDefault();
26		$('body,html').animate({
27			scrollTop: 0 ,
28		 	}, scroll_top_duration
29		);
30	});
31
32});