https://sew-drive.ru/font/js/scrollTo.js

1$(function() {
2			var scroll_timer;
3			var displayed = false;          
4			var $message = $('#message');
5                        var $messagedown = $('#messagedown');
6			var $window = $(window);
7                        var top = $(document.body).children(0).position().top;
8                           
9			$window.scroll(function () {
10				window.clearTimeout(scroll_timer);
11				scroll_timer = window.setTimeout(function () { // use a timer for performance
12					if($window.scrollTop() <= top) // hide if at the top of the page
13					{
14                                                displayed = false;
15						$message.fadeOut(0);
16                                                $messagedown.fadeIn(0);   
17					}
18					else if(displayed == false) // show if scrolling down
19					{
20                                                displayed = false;
21                                                $message.fadeIn(0);
22                                                $messagedown.fadeOut(0);                                            
23					}
24                                });
25			});
26		});
27
28$(function() {
29				var $elem = $('#art-main');									
30				$('#messagedown').click(
31					function (e) {
32						$('html, body').animate({scrollTop: $elem.height()}, 800);
33					}
34				);
35				$('#message').click(
36					function (e) {
37						$('html, body').animate({scrollTop: '0px'}, 800);
38					}
39			 );
40		});