https://www.rvpark-takinomiya.com/common/js/scrollAnimation.js

1var scrollAnimationClass = 'sa';
2var scrollAnimationShowClass = 'show';
3var triggerMarginDefault = 100;
4
5var scrollAnimationElm = document.querySelectorAll('.' + scrollAnimationClass);
6var scrollAnimationFunc = function() {
7  var dataMargin = scrollAnimationClass + '_margin';
8  var dataTrigger = scrollAnimationClass + '_trigger';
9  var dataDelay = scrollAnimationClass + '_delay';
10  for(var i = 0; i < scrollAnimationElm.length; i++) {
11    var triggerMargin = triggerMarginDefault;
12    var elm = scrollAnimationElm[i];
13    var showPos = 0;
14    if(elm.dataset[dataMargin] != null) {
15      triggerMargin = parseInt(elm.dataset[dataMargin]);
16    }
17    if(elm.dataset[dataTrigger]) {
18      showPos = document.querySelector(elm.dataset[dataTrigger]).getBoundingClientRect().top + triggerMargin;
19    } else {
20      showPos = elm.getBoundingClientRect().top + triggerMargin;
21    }
22    if (window.innerHeight > showPos) {
23      var delay = (elm.dataset[dataDelay])? elm.dataset[dataDelay] : 0;
24      setTimeout(function(index) {
25        scrollAnimationElm[index].classList.add('show');
26      }.bind(null, i), delay);
27    }
28  }
29}
30window.addEventListener('load', scrollAnimationFunc);
31window.addEventListener('scroll', scrollAnimationFunc);