監聽滾動條

 mounted(){
   window.addEventListener('scroll', this.handleScroll);
 }
 
 method:{
 // 監聽滾動事件
 handleScroll () {


bindScroll(event) {
// console.log(event)
// 滾動的高度
const scrollTop =
(event.srcElement
? event.srcElement.documentElement.scrollTop
: false) ||
window.pageYOffset ||
(event.srcElement ? event.srcElement.body.scrollTop : 0);
// 視窗高度
const clientHeight =
(event.srcElement && event.srcElement.documentElement.clientHeight) ||
document.body.clientHeight;
// 頁面高度
const scrollHeight =
(event.srcElement && event.srcElement.documentElement.scrollHeight) ||
document.body.scrollHeight;
// 距離頁面底部的高度
const height = scrollHeight - scrollTop - clientHeight;

// console.log(height, scrollHeight, scrollTop, clientHeight);
},

},
 
 }
  
 destroyed () {  //  記得銷毀監聽不然耗性能
 window.removeEventListener('scroll', this.handleScroll)
 },