//点击导航铆钉到指定位置            goDetails(index) {                this.current = index;                let height = Number(this.$refs['navleft'].offsetHeight)// 导航的高度                let toTop = this.$refs.single[index].offsetTop  // index对应内容的高度                let total = index === 0 ? toTop - height - 10 : toTop - height + index - 15 　　　　　　　　　　//减去导航的高度和margin-tbottom的高度为滚动高度                let distance = document.documentElement.scrollTop || document.body.scrollTop                let step = total / 20                 if (total > distance) {                     let newTotal = total - distance                    step = newTotal / 20                    smoothDown()                } else {                    let newTotal = distance - total                         step = newTotal / 20                    smoothUp()                }                function smoothDown() {                    if (distance < total) {                    distance += step                    document.body.scrollTop = document.documentElement.scrollTop = distance                    setTimeout(smoothDown, 10)                    } else {                    document.body.scrollTop = document.documentElement.scrollTop = total                    }                }                function smoothUp() {                    if (distance > total) {                    distance -= step                    document.body.scrollTop = document.documentElement.scrollTop = distance                    setTimeout(smoothUp, 10)                    } else {                    document.body.scrollTop = document.documentElement.scrollTop = total                    }                }            },