https://www.karatetsu.com/concept/concept.js?2002031843

1/* a-button */
2$(function(){
3  $('a[href^="#"]').click(function(){
4    var href= $(this).attr("href");
5    var target = $(href == "#" || href == "" ? 'html' : href);
6    var position = target.offset().top;
7	$('body,html').animate({scrollTop: position}, 500);
8    return false;
9  });
10
11    var showFlag = false;
12    var topBtn = $('#page-top');
13    $(window).scroll(function () {
14        if ($(this).scrollTop() > 100) {
15            if (showFlag == false) {
16                showFlag = true;
17                topBtn.addClass('page-top-button-show');
18            }
19        } else {
20            if (showFlag) {
21                showFlag = false;
22                topBtn.removeClass('page-top-button-show');
23            }
24        }
25    });
26    topBtn.click(function () {
27        $('body,html').animate({
28            scrollTop: 0
29        }, 500);
30        return false;
31    });
32
33  var $win = $(window);
34  windowMinus = 0;
35
36  $win.on('load resize', function() {
37    var windowWidth = window.innerWidth;
38
39    if (windowWidth < 720) {
40      windowMinus = 0;
41    }
42    else {
43      windowMinus = 100;
44    }
45  });
46
47    $(window).scroll(function (){
48        $('.fadein').each(function(){
49            var elemPos = $(this).offset().top;
50            var scroll = $(window).scrollTop();
51            var windowHeight = $(window).height();
52            if (scroll > elemPos - windowHeight + windowMinus){
53              $(this).addClass('scrollin');
54            }
55        });
56    });
57	$(window).scroll(function(){
58			var elemPos02 = $('#footer-section').offset().top;
59			var scroll = $(window).scrollTop();
60			var windowHeight = $(window).height();
61			if (scroll > elemPos02 - windowHeight + 35){
62				$('#page-top').css('background', '#ec6a51');
63			} else {
64				$('#page-top').css('background', '#000');
65			}
66	});
67});
68
69/* inoutban */
70document.documentElement.addEventListener('touchstart', function (e) {
71if (e.touches.length >= 2) {e.preventDefault();}
72}, false);
73var t = 0;
74document.documentElement.addEventListener('touchend', function (e) {
75var now = new Date().getTime();
76if ((now - t) < 350){
77  e.preventDefault();
78}
79t = now;
80}, false);
81
82$(window).load(function(){
83	$('html').addClass('onload');
84});