代码简写

[Rabbitzzc]

/*向下滚动*/
if (distance < top) {
    let small_interval = (top - distance) / 50
    let i = 0
    let timer = setInterval(() => {
        i++
        // console.log(distance += small_interval)
        document.documentElement.scrollTop = distance
        if (i == 50) {
            clearInterval(timer)
        }
    }, 10)
}
/*向上滚动*/
else if (distance > top) {
    let small_interval = (distance - top) / 50
    let i = 0
    let timer = setInterval(() => {
        i++
        // console.log(distance -= small_interval)
        document.documentElement.scrollTop = distance
        if (i == 50) {
            clearInterval(timer)
        }
    }, 10)
}
=========>可以简写为下面的样式。
// top-distance，如果>0向下滚动，如果<0向上滚动，直接使用
let small_interval = (top - distance) / 50
// console.log(small_interval)
if(small_interval !== 0) {
    let i = 0
    let timer = setInterval(() => {
        i++
        distance += small_interval
        document.documentElement.scrollTop = distance
        if (i == 50) {
            clearInterval(timer)
        }
    }, 10)
}

[Rabbitzzc]

这里就是加上负数，等于减去正的