vue做出可搜索下拉框

<template>
 <p class="vue-dropdown default-theme" v-show-extend="show">
 <p class="search-module clearfix" v-show="length">
 <input class="search-text" 
 @keyup='search($event)' :placeholder="placeholder" />
 <span class="glyphicon glyphicon-search search-icon"></span>
 </p>
 <ul class="list-module" v-show="length">
 <li v-for ="(item,index) in datalist" @click="appClick(item)" 
 :key="index">
 <span class="list-item-text">{{item.name}}</span>
 </li>
 </ul>
 <p class="tip__nodata" v-show="!datalist.length">{{nodatatext}}</p>
 </p>
</template>
<script>
 export default {
 data(){
 return {
 _datalist:this.itemlist.concat(),
 datalist:this.itemlist.concat(),
 length:this.itemlist.length
 }
 },
 props:{
 'show':{//用于外部控制组件的显示/隐藏
 type:Boolean,
 default:true
 },
 'itemlist':Array,
 'placeholder':String,
 'nodatatext':String
 },
 directives:{
 'show-extend':function(el,binding,vnode){//bind和 update钩子
 let value = binding.value,searchInput = null;
 if(value){
 el.style.display='block';
 }else{//隐藏后，恢复初始状态
 el.style.display='none';
 searchInput = el.querySelector(".search-text");
 searchInput.value = '';
 vnode.context.datalist = vnode.context.itemlist;//还原渲染数据
 }
 }
 },
 methods:{
 appClick:function(data){
 this.$emit('item-click',data);
 },
 search:function(e){
 let vm = this,searchvalue = e.currentTarget.value;
 vm.datalist = vm.$data._datalist.filter(function(item,index,arr){
 return item.name.indexOf(searchvalue) != -1;
 });
 }
 },
 mounted:function(){
 }
 }
</script>
<style lang="scss" scoped>
 .vue-dropdown.default-theme {
 position: absolute;
 left:15%;
 display: none;
 width: 70%;
 margin: 0 auto;
 margin-top: 1em;
 padding: 1em;
 z-index:10;
 box-shadow: 0px 0px 10px #ccc;
 &._self-show {
 display: block!important;
 }
 .search-module {
 position: relative;
 .search-text {
 width: 100%;
 height: 30px;
 padding-right: 2em;
 padding-left:0.5em;
 border-radius: 0.5em;
 box-shadow: none;
 border: 1px solid #ccc;
 &:focus {
 border-color: #2198f2;
 }
 }
 .search-icon {
 position: absolute;
 top: 24%;
 right: 0.5em;
 color: #aaa;
 }
 }
 .list-module {
 max-height: 200px;
 overflow-y: auto;
 li {
 &._self-hide {
 display: none;
 }
 margin-top: 0.5em;
 padding: 0.5em;
 &:hover {
 cursor:pointer;
 color: #fff;
 background: #00a0e9;
 }
 }
 }
 }
 .tip__nodata {
 font-size: 12px;
 margin-top: 1em;
 }
</style>

<dropdown :itemlist="itemlist" :placeholder="placeholder" :nodatatext="nodatatext"></dropdown>