자바스크립트 스크롤 애니메이션 질문입니다~~

<script>

      // Scroll Animation (sa, 스크롤 애니메이션)

      const saTriggerMargin = 300;

      const saElementList = document.querySelectorAll('.sa');

 

      const saFunc = function() {

        for (const element of saElementList) {

          if (!element.classList.contains('show')) {

            if (window.innerHeight > element.getBoundingClientRect().top + saTriggerMargin) {

              element.classList.add('show');

            } else if (window.innerHeight < element.getBoundingClientRect().top + saTriggerMargin) {

                element.classList.remove('show');

            }

          }

        }

      }

 

      window.addEventListener('load', saFunc);

      window.addEventListener('scroll', saFunc);

    </script>