vue计算滚动条滚动速度

handleScroll() {
      var scrollTop =
        document.documentElement.scrollTop || document.body.scrollTop;
      //如何计算滚动速度???
      //利用定时器，来计算滚动速度(滚动条在timeScale没有被连续滚动则结束间隔)
      let distance = 0,
        startTimer = null,
        beginTime = 0,
        speed = 0;
      const timeScale = 100; //检测滚动停止的时间
      window.onscroll = () => {
        let tempScrollTop =
          document.documentElement.scrollTop || document.body.scrollTop;
        distance += tempScrollTop - scrollTop; //间隔时间内滑动的距离（+向下，-向上）
        console.log('distance',distance)
        scrollTop = tempScrollTop; //下一次滚动开始时滚动条初始位置
        clearTimeout(startTimer); //清除开始定时器
        if (!beginTime) {
          beginTime = new Date().getTime(); //如果timer为0,则开始滚动,则获取起始时间
          //console.log(beginTime)
        }
        startTimer = setTimeout(() => {
          //设置开始定时器
          let overTime = new Date().getTime(); //延时500ms后，滚动后结束的时间
          //console.log(overTime)
          let diffTimer = (overTime - beginTime - timeScale) / 1000; //时间差 = 结束-开始-500ms
          speed = distance / diffTimer;
          distance = 0; //间隔距离归零
          beginTime = 0; //起始时间
          console.log('speed',speed);
        }, timeScale);
      };
    }