https://www.inkuele.de/bundles/uitotop/js/jquery.ui.totop.min.js?v=c4ca4238

1/* UItoTop jQuery Plugin 1.2 | Matt Varone | http://www.mattvarone.com/web-design/uitotop-jquery-plugin */
2(function ($) {
3  $.fn.UItoTop = function (options) {
4    var defaults = {
5        text: 'To Top',
6        min: 200,
7        inDelay: 600,
8        outDelay: 400,
9        containerID: 'toTop',
10        containerHoverID: 'toTopHover',
11        scrollSpeed: 1200,
12        easingType: 'linear'
13      }, settings = $.extend(defaults, options), containerIDhash = '#' + settings.containerID,
14      containerHoverIDHash = '#' + settings.containerHoverID;
15    $('body').append('<a id="' + settings.containerID + '">' + settings.text + '</a>');
16    $(containerIDhash).hide().on('click.UItoTop', function () {
17      $('html, body').animate({scrollTop: 0}, settings.scrollSpeed, settings.easingType);
18      $('#' + settings.containerHoverID, this).stop().animate({'opacity': 0}, settings.inDelay, settings.easingType);
19      return false;
20    }).prepend('<span id="' + settings.containerHoverID + '"></span>').hover(function () {
21      $(containerHoverIDHash, this).stop().animate({'opacity': 1}, 600, 'linear');
22    }, function () {
23      $(containerHoverIDHash, this).stop().animate({'opacity': 0}, 700, 'linear');
24    });
25    $(window).scroll(function () {
26      var sd = $(window).scrollTop();
27      if (typeof document.body.style.maxHeight === "undefined") {
28        $(containerIDhash).css({'position': 'absolute', 'top': sd + $(window).height() - 50});
29      }
30      if (sd > settings.min)
31        $(containerIDhash).fadeIn(settings.inDelay); else
32        $(containerIDhash).fadeOut(settings.Outdelay);
33    });
34  };
35})(jQuery);