实践加深对vue的理解和运用有效途径，本文是基于vue的可搜索下拉框定制组件实现，在此记录.

一、效果

二、组件代码
dropdown.vue

<template>
    <div class="vue-dropdown default-theme" v-show-extend="show">
        <div class="search-module clearfix" v-show="itemlist.length">
            <input class="search-text" 
            @keyup='search($event)' :placeholder="placeholder" />
            <span class="glyphicon glyphicon-search search-icon"></span>
        </div>
        <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>
        <div class="tip__nodata" v-show="!length">{{nodatatext}}</div>
    </div>
</template>

<script>
    export default {
        data(){
            return {
                datalist:[]
            }
        },
        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
        },
        watch:{
            itemlist:function(val){
                this.datalist = val.concat();
            }
        },
        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.itemlist.filter(function(item,index,arr){
                    return item.name.indexOf(searchvalue) != -1;
                });
            }
        },
        computed:{
            length:function(){
                return this.datalist.length;
            }
        }
    }
</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>

三、组件使用

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