vue獲取滾動條距離

function getScrollTop(){

  let scrollTop = 0;

  if(document.documentElement && document.documentElement.scrollTop){

    scrollTop = document.documentElement.scrollTop;

  } else if(document.body){

    scrollTop = document.body.scrollTop;

  }

  return scrollTop;

}
window.onscroll = function(){

  console.log(getScrollTop());
}