https://programmailfuturo.it/media/plg_system_sl_scrolltotop/js/scrolltotop_jq.js

1/**
2 * @copyright	Copyright (c) 2013 Skyline Software (http://extstore.com). All rights reserved.
3 * @license		GNU General Public License version 2 or later; see LICENSE.txt
4 */
5
6(function ($) {
7	$.fn.SLScrollToTop	= function(options) {
8		var defaults	= {
9			'id':			'scrollToTop',
10			'className':	'scrollToTop',
11			'image':		'',
12			'text':			'^ Scroll to Top',
13			'title':		'Scroll to Top',
14			'duration':		500
15		};
16		
17		var options		= $.extend(defaults, options);
18		var $link		= $('<div />', {
19			'id':		options.id,
20			'html':		options.text,
21			'title':	options.title,
22			'class':	options.className
23		}).appendTo('body').hide();
24
25		if (options.image != '') {
26			$('<img src="' + options.image + '" alt="' + options.title + '" />').prependTo($link);
27		}
28
29		$(window).scroll(function() {
30			$this	= $(this);
31
32			if ($this.scrollTop() != 0) {
33				$link.fadeIn();
34			} else {
35				$link.fadeOut();
36			}
37		});
38
39		$link.click(function () {
40			$('body,html').animate({
41				scrollTop: 0
42			}, options.duration);
43		});
44	}
45})(jQuery);