<template>
 <div id="app">
 <nav class="sidebar">
 <ul class="menu">
 <li v-for="(navList,index) in navLists"
  :key="index"
  class="forRealitive"
  v-on:mouseover="showToggle(index)"
  v-on:mouseout="handleHide"
 >
  <a class="sidebar-link" 
  :href="navList.eTitle" " 
  >{{navList.title}}</a>
  <ul class="menu-sub"
  v-show="index===isShow">
  <li v-for="(item,idx) in navList.child" 
  :key="idx"
  >
  <a class="section-link" 
   :href="item.esubTitle" " 
   v-on:click="handleHide"
  >{{item.subTitle}}</a>
  </li>
  </ul>
 </li>
 </ul>
 </nav>
 </div>
</template>

navLists:[
 {
 'title':'项目信息',
 'eTitle':'#projectMessage',
 'child':[
 {
 'subTitle':'项目简介',
 'esubTitle':'#projectIntroduction'
 },
 {
 'subTitle':'样品信息',
 'esubTitle':'#sampleInformation'
 }
 ]
 },
 {
 ...
 }
 ...
]
isShow:0

mounted: function () {
 // 避免第一个渲染的显示
 this.isShow = -1
 },
 methods: {
 showToggle: function (index) {
 this.isShow = index
 },
 handleHide: function () {
 this.isShow = !this.isShow
 }
 }