从零开始封装自己的自定义Vue组件

<template>
<div class="selectWrap">
 <div class="select-wrapper">
  <div class="select" @click = "triggerOption">
   <div class="select-content">{{selectContent.text}}</div>
   <div class="triangle-wrapper">
    <div id="triangle-down"></div>
   </div>
  </div>
  <div class="option-wrapper" style="display: none;">
   <div class="option-item" v-for = "(item,index) in subject" :key="index" @mouseout="out($event)" @mouseover="move($event)" @click = "choose(item)">{{item.text}}</div>
  </div>
 </div>
</div>
</template>
<script>
 export default{
  data(){   return{    selectContent:{value:0,text:"小张"}, //模拟select默认选中的值
    subject:[{value:0,text:"小张"},{value:1,text:"小李"}， //模拟option中的文本和value值
         {value:2,text:"小王"}，{value:4,text:"小明"}], 
   }
  },
  computed:{
   optionWrapper(){    return document.querySelector(".option-wrapper");
   },
   selectCon(){    return document.querySelector(".select-content");
   },
   subjectList(){    return document.getElementsByClassName("option-item");
   },
  },
  methods:{
   move(event){ //模拟hover效果    for(var item of this.subjectList){
     item.classList.remove("hover");
    }
    event.currentTarget.classList.add("hover");
   },
   out(event){
    event.currentTarget.classList.remove("hover");
   },
   triggerOption(){ //控制option的展示，以及选中后的高亮效果    if (this.optionWrapper.style.display == "none") {     this.optionWrapper.style.display = "block";
    }else{     this.optionWrapper.style.display = "none";
    }    for(var item of this.subjectList){     if (item.innerHTML == this.selectContent.text) {
      item.classList.add("hover");
     }else{
      item.classList.remove("hover");
     }
    }
   },   choose(item){ //选中“option”    this.selectContent.text = item.text;
    this.optionWrapper.style.display = "none";
   }
  },
 }</script>
<style>
 .selectWrap{ /*select的宽度*/
  width: 100px;
 }
 .select{
  position: relative;
  overflow: hidden;
  padding-right: 10px;
  min-width: 80px;
  width: 100%;
  height: 20px;
  line-height: 20px;
  border: 1px solid #000;
  cursor: default;
  font-size: 13px;
 }
 .select-content{
  text-align: left;
 }
 .triangle-wrapper{
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 20px;
  background-color: #fff;
  cursor: default;
 }
 #triangle-down{
  position: absolute;
  right: 5px;
  top: 50%;
  transform: translateY(-50%);
  width: 0;
  height: 0;
  border-left: 3px solid transparent;
  border-right: 3px solid transparent;
  border-top: 6px solid #000;
 }
 .option-wrapper{
  position: relative;
  overflow: hidden;
  min-width: 80px;
  width: 100%;
  border-right: 1px solid #000;
  border-bottom: 1px solid #000;
  border-left: 1px solid #000;
 }
 .option-item{
  min-width: 80px;
  height: 20px;
  line-height: 20px;
  padding-right: 10px;
  text-align: left;
  cursor: default; 
 }
 .hover{
  background-color: rgb(30,144,255);
  color:#fff !important;
 }</style>  

<template>
 ......</template>
<script>
 export default{  props:["subject","selectContet"，"selectWidth”],
  mounted(){   document.querySelector(".selectWrap").style.width = 
   this.selectWidth+"px";
  },
  computed:{
   optionWrapper(){    return document.querySelector(".option-wrapper");
   },
   selectCon(){    return document.querySelector(".select-content");
   },
   subjectList(){    return document.getElementsByClassName("option-item");
   },
  },
  methods:{
   ......
   choose(item){    this.selectContent.text = item.text;    this.optionWrapper.style.display = "none";
   }
  },
 }</script>
<style> /*.selectWrap{
  width: 100px;
 }*/
 ....... </style>

<template>
 ......</template>
<script>
 export default{  props:{
   selectWidth:{
    type:Number,    default:100,
   },
   subject:{
    type:Array,
    default:function(){
     return []
    }
   },
   selectContent:{
    type:Object,
    default:function(){
     return {value:0,text:"请选择"}
    }
   },
  },
  mounted(){
   document.querySelector(".selectWrap").style.width = this.selectWidth+"px";
  },
  ...... 
  methods:{
   ......
   choose(item){    this.selectContent.text = item.text;    this.optionWrapper.style.display = "none";
   }
  },
 }</script>
<style>
 ......</style>

choose(item,value){
  this.selectContent.text = item.text;
  this.optionWrapper.style.display = "none";
  this.$emit("changeSelect",this.selectContent.text,this.selectContent.value);
}