jump (index) {
 let jump = document.querySelectorAll('.d_jump')
 // 獲取需要滾動(dòng)的距離
 let total = jump[index].offsetTop
 // Chrome
 document.body.scrollTop = total
 // Firefox
 document.documentElement.scrollTop = total
 // Safari
 window.pageYOffset = total
},

$('html body').animate({scrollTop: total}, 500);

// 平滑滾動(dòng)，時(shí)長(zhǎng)500ms，每10ms一跳，共50跳
// 獲取當(dāng)前滾動(dòng)條與窗體頂部的距離
let distance = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop
// 計(jì)算每一小段的距離
let step = total / 50
(function smoothDown () {
 if (distance < total) {
 distance += step
　　// 移動(dòng)一小段
 document.body.scrollTop = distance
 document.documentElement.scrollTop = distance
 window.pageYOffset = distance
　　// 設(shè)定每一次跳動(dòng)的時(shí)間間隔為10ms
 setTimeout(smoothDown, 10)
 } else {
　　// 限制滾動(dòng)停止時(shí)的距離
 document.body.scrollTop = total
 document.documentElement.scrollTop = total
 window.pageYOffset = total
 }
})()

jump (index) {
 // 用 class="d_jump" 添加錨點(diǎn)
 let jump = document.querySelectorAll('.d_jump')
 let total = jump[index].offsetTop
 let distance = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop
 // 平滑滾動(dòng)，時(shí)長(zhǎng)500ms，每10ms一跳，共50跳
 let step = total / 50
 if (total > distance) {
 smoothDown()
 } else {
 let newTotal = distance - total
 step = newTotal / 50
 smoothUp()
 }
 function smoothDown () {
 if (distance < total) {
 distance += step
　　　　　　　document.body.scrollTop = distance
 document.documentElement.scrollTop = distance
 window.pageYOffset = distance
 setTimeout(smoothDown, 10)
 } else {
 document.body.scrollTop = total
 document.documentElement.scrollTop = total
 window.pageYOffset = total
 }
 }
 function smoothUp () {
 if (distance > total) {
 distance -= step
　　　　　　　document.body.scrollTop = distance
 document.documentElement.scrollTop = distance
 window.pageYOffset = distance
 setTimeout(smoothUp, 10)
 } else {
 document.body.scrollTop = total
 document.documentElement.scrollTop = total
 window.pageYOffset = total
 }
 } 
 }

mounted: function () {
 this.$nextTick(function () {
 window.addEventListener('scroll', this.onScroll)
 })
 },
 methods: {
 onScroll () {
 let scrolled = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop
　　　 // 586、1063分別為第二個(gè)和第三個(gè)錨點(diǎn)對(duì)應(yīng)的距離
 if (scrolled >= 1063) {
 this.steps.active = 2
 } else if (scrolled < 1063 && scrolled >= 586) {
 this.steps.active = 1
 } else {
 this.steps.active = 0
 }
 }
 }