SOURCE

let VSelect=Vue.extend({
  template:"#vselect",
  props:{
    selections:{
      type:Array,
      default:[{
        label:'',
        value:0
      }]
    }
  },
  methods:{
    toggleDrop (){
      this.isDrop=!this.isDrop
    },
    chooseSelection(index){
      this.nowIndex=index
      this.isDrop=false
      console.log('触发自定义事件on-change传给父元素的元素是--'+this.selections[this.nowIndex].label+":"+this.selections[this.nowIndex].value);
      this.$emit('on-change',this.selections[this.nowIndex])
    }
  },
  data() {
    return {
      isDrop:false,
      nowIndex:0
    }
  },
})


new Vue({
  el:"#parent",
  components:{
    'VSelect':VSelect
  },
  data:{
    options:[
      {label:'answer1',value:0},
      {label:'answer2',value:1},
      {label:'answer3',value:2},
      {label:'answer4',value:3}
    ],
    answer:{
      label:'--',value:0
    }
  },
  methods:{
    setAnswer(attr,val){
      console.log(attr,val)
      this[attr]=val;
    }
  }
})

<div id="parent">
  <v-select :selections="options" @on-change="setAnswer('answer',$event)"></v-select>
  
  <p>{{this.answer}}</p>
</div>

<template id="vselect">
  <div class="selection-component">
    <div class="selection-show" @click="toggleDrop">
      <span>{{selections[nowIndex].label}}</span>
      <div class="arrow"></div>
    </div>
    <div class="selection-list" v-if="isDrop">
      <ul>
        <li v-for="(item,index) in selections" @click="chooseSelection(index)">
          {{item.label}}
        </li>
      </ul>
    </div>
  </div>
</template>

.selection-component {
    position: relative;
    display: inline-block;
  }
  .selection-show {
    border: 1px solid #e3e3e3;
    padding: 0 20px 0 10px;
    display: inline-block;
    position: relative;
    cursor: pointer;
    height: 25px;
    line-height: 25px;
    border-radius: 3px;
    background: #fff;
  }
  .selection-show .arrow {
    display: inline-block;
    border-left: 4px solid transparent;
    border-right: 4px solid transparent;
    border-top: 5px solid #e3e3e3;
    width: 0;
    height: 0;
    margin-top: -1px;
    margin-left: 6px;
    margin-right: -14px;
    vertical-align: middle;
  }
  .selection-list {
    display: inline-block;
    position: absolute;
    left: 0;
    top: 25px;
    width: 100%;
    background: #fff;
    border-top: 1px solid #e3e3e3;
    border-bottom: 1px solid #e3e3e3;
    z-index: 5;
  }
.selection-list ul {
  margin:0;
  padding:0;
}
  .selection-list li {
    padding: 5px 15px 5px 10px;
    border-left: 1px solid #e3e3e3;
    border-right: 1px solid #e3e3e3;
    cursor: pointer;
    background: #fff;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;

  }
  .selection-list li:hover {
    background: #e3e3e3;
  }