[javaScript] 제이쿼리 없이 자바스크립트 top 버튼 만들기

scrollTop('js-button', 500);
function scrollTop(elem,duration) {
     let target = document.getElementById(elem);

     target.addEventListener('click', function() {
          let currentY = window.pageYOffset; 
          let step = duration/currentY > 1 ? 10 : 100;
          let timeStep = duration/currentY * step;
          let intervalID = setInterval(scrollUp, timeStep);

          function scrollUp(){
               currentY = window.pageYOffset;
               if(currentY === 0) {
              clearInterval(intervalID);
              } else {
                    scrollBy( 0, -step );
               }
          }
     });
}

 

참고

ponyozzang.tistory.com/214