vue返回上一頁面時回到原先滾動的位置的方法

<template>
 <div id="app">
 <!--<router-view/>-->
 <!--頁面返回不刷新-->
 <keep-alive>
 <router-view v-if="$route.meta.keepAlive"></router-view>
 </keep-alive>
 <router-view v-if="!$route.meta.keepAlive"></router-view>
 </div>
</template>

export default new Router({
 routes: [{
 path: '/',
 name: 'index',
 component: index,
 meta: {
 keepAlive: true
 }
 },

//在頁面離開時記錄滾動位置
beforeRouteLeave (to, from, next) {
 this.scrollTop = document.documentElement.scrollTop || document.body.scrollTop
 next()
 },

//進入該頁面時，用之前保存的滾動位置賦值
beforeRouteEnter (to, from, next) {
 next(vm => {
 document.body.scrollTop = vm.scrollTop
 })
 },