vue实现带过渡效果的下拉菜单功能

export const clickOutside = {
 bind(el, binding, vnode) {
 function documentHandler(e) {
 if (el.contains(e.target)) {
 return false;
 }
 if (binding.expression) {
 binding.value(e);
 }
 }
 el.__vueClickOutside__ = documentHandler;
 document.addEventListener("click", documentHandler);
 },
 update() {},
 unbind(el, binding) {
 document.removeEventListener("click", el.__vueClickOutside__);
 delete el.__vueClickOutside__;
 }
};

 <div class="info-select">
 <div class="select">
 <p class="select-p" @click="showSelectUl('s1')" v-clickOutside="hideSelectUl">
 <span>{{issues}}</span>
 <img :src="require('../../assets/images/support/icon_xiala.png')" alt="">
 </p>
 <transition name="slide-fade">
 <div class="select-ul" v-show="!showIssues" >
 <div v-for="(item, index) in list" :key="index" >
 <div>{{item.class}}</div>
 <div v-for="(item1, i) in item.node" :key="i" @click="getSize('s1', item1.class, index, i)">
 <p :class="{active:item == issues}">{{item1.class}}</p>
 </div>
 </div>
 </div>
 </transition>
 <transition leave-active-class="slideOutRight" enter-active-class="slideInRight">
 <p class="animated errP"  v-show="form.issueErr" >{{form.issueMsg}}</p>
 </transition>
 </div>
 <div class="select">
 <p class="select-p" @click="showSelectUl('s2')" v-clickOutside="hideSelectUl2">
 <span>{{issues2}}</span>
 <img :src="require('../../assets/images/support/icon_xiala.png')" alt="">
 </p>
 <transition name="component-fade" mode="out-in">
 <div class="select-ul" v-show="!showIssues2">
 <p v-for="(item, index) in childList" :class="{active:item == issues2}"
 :key="index" @click="getSize('s2', item.class, index)">{{item.class}}</p>
 </div>
 </transition>
 <transition leave-active-class="slideOutUp" enter-active-class="slideInUp">
 <p class="animated errP"  v-if="form.issueErr1" >{{form.issueMsg1}}</p>
 </transition>
 </div>
 </div>
 <div class="p-bts clearafter">
 <button @click="form.issueErr = !form.issueErr">p1</button>
 <button @click="form.issueErr1 = !form.issueErr1">p2</button>
 </div>

import { clickOutside } from 'Models/clickoutside.js';
export default {
 data(){
 return{
 catogery:'flight',
 issues:"Select Category",
 issues2:"Select Issue",
 showIssues:true,
 showIssues2:true,
 list:[
 {id:0,class:'flight',node:[
 {class:'1.1 a1111111111111 11111111111111',node:[
 {class:'问题a1?'},
 {class:'问题a2?'}
 ]},
 {class:'1.2 a2',node:[
 {class:'问题a3?'},
 {class:'问题a4?'}
 ]},
 ]},
 {id:1,class:'hotel',node:[
 {class:'1.1 b1',node:[
 {class:'问题b1?'},
 {class:'问题b2?'}
 ]},
 {class:'1.2 b2',node:[
 {class:'问题b3?'},
 {class:'问题b4?'}
 ]},
 ]},
 ],
 childList:[],
 form:{
 issueMsg:"Please select a category",issueErr:true,
 issueMsg1:"Please select a issue",issueErr1:true,
 },
 }
 },
 methods: {
 hideSelectUl(){
 this.showIssues = true;
 },
 hideSelectUl2(){
 this.showIssues2 = true;
 },
 showSelectUl(s){
 if(s == 's1'){
 this.showIssues = !this.showIssues;
 this.showIssues2 = true;
 }else{
 this.showIssues = true;
 this.showIssues2 = !this.showIssues2;
 }
 },
 getSize(s, val, index, index2){
 if(s == 's1'){
 this.issues = val;
 this.showIssues = true;
 this.catogery = this.list[index].class;
 this.childList = this.list[index].node[index2].node;
 this.issues2 = 'Select Issue';
 }else if(s == 's2'){
 this.issues2 = val;
 this.showIssues2 = true;
 }
 },
 },
 directives:{
 clickOutside,
 }
}

.info-select{
 display: flex;
 justify-content: space-between;
 .select{
 width:40%;
 position: relative;
 padding:0.1rem 3% 0.1rem;
 vertical-align: top;
 font-size: 0.15rem;
 border-radius:2px;
 background: #fff;
 border-top:1px solid #ddd;
 border-bottom:1px solid #ddd;
 border-right:1px solid #ddd;
 }
 .select:last-child{
 border-right:0;
 border-top:1px solid #ddd;
 border-bottom:1px solid #ddd;
 border-left:1px solid #ddd;
 }
 .select-p{
 position: relative;
 height:0.21rem;
 line-height:0.21rem;
 span{
 font-size: 0.16rem;
 display: inline-block;
 width:90%;
 overflow:hidden;
 white-space:nowrap;
 text-overflow:ellipsis;
 }
 img{
 display:block;
 width:0.12rem;
 position: absolute;
 right: 0;
 top: 0;
 vertical-align: middle;
 }
 }
 .select-ul{
 width:93.5%;
 padding:0.12rem 3%;
 position: absolute;
 top: 0.42rem;
 left: 0;
 z-index: 12;
 background: #fff;
 border:1px solid #eee;
 p{
 padding:0.1rem 0 0.1rem 0.1rem;
 overflow:hidden;
 white-space:nowrap;
 text-overflow:ellipsis;
 }
 p:hover{
 background: #eee;
 }
 p.active{
 background: #eee;
 }
 }
 .errP{
 color:#f00;
 }
 }
 .p-bts{
 margin-top: 0.4rem;
 zoom: 1;// zoom(IE转有属性)可解决ie6,ie7浮动问题
 button{
 width:1.5rem;
 height:0.4rem;
 background: #ffa000;
 float: left;
 color:#fff;
 font-size:0.25rem;
 border-radius:2px;
 }
 button:last-child{
 float: right;
 }
 }

 .component-fade-enter-active, .component-fade-leave-active {
 transition: opacity .3s ease;
 }
 .component-fade-enter, .component-fade-leave-to
 /* .component-fade-leave-active for below version 2.1.8 */ {
 opacity: 0;
 }
 // css animate
 .slide-fade-enter-active{
 transition:all .2s ease-in;
 }
 .slide-fade-leave-active {
 transition: all .2s cubic-bezier(1.0, 0.5, 0.8, 1.0);
 }
 .slide-fade-enter, .slide-fade-leave-to{
 /* .slide-fade-leave-active for below version 2.1.8 */ 
 transform: translateY(20px);
 opacity: 0;
 }

 // bounce
 .bounce-enter-active {
 animation: bounce-in .2s;
 }
 .bounce-leave-active {
 animation: bounce-in .1s reverse;
 }
 @keyframes bounce-in {
 0% {
 transform: scale(0);
 }
 50% {
 transform: scale(1);
 }
 100% {
 transform: scale(1);
 }
 }