vue日志之如何用select选中默认值

     <div class="item">
        <p class="top">
          <span>推广物：</span>
          <select v-model="detail.aid">
            <option :value="item.id" v-for="item in accountList" :key="item.id">{{item.name}}</option>
          </select>
        </p>
        <h6 class="bottom">选择推广任务的公众号</h6>
      </div>

  data() {
    return {
      detail: {
        aid: 0,
      },
      accountList: [],
      ...
    };
  },
 
  methods: {
    getAccountList() {
      //获取公众号
      this.$fetch(`/popularize/account/list/2`).then(response => {
        if (response.errorCode == 0) {
          let data = response.data;
          this.accountList = data;
        }
      });
    },
  }

  mounted() {
    ...
    this.getAccountList();
    document.getElementsByTagName('select').selectIndex = 0
    // console.log('sid',document.getElementsByTagName('select').selectIndex )
  },

  created () {
    // select初始化
 
    this.detail.aid = this.accountList[0].id; //默认选中第一项
 
  },

  mounted() {
    // select初始化
    this.$fetch(`/popularize/account/list/2`).then(response => {
      if (response.errorCode == 0) {
        let data = response.data;
        this.accountList = data;
        this.detail.aid = this.accountList[0].id; //默认选中第一项 初始化
      }
    });
  },

        <p class="top">
          <span>广告限量模式：</span>
          <select v-model="detail.mode">
            <option :value="0">全选</option>
            <option :value="1">每日限量广告</option>
            <option :value="2">不限量广告</option>
          </select>
        </p>

  data() {
    return {
      detail: {
        ...
        aid: 0,
        mode: 0,
      },
  }

<div id="companylist">
    <label>所属公司</label> 
      <select class="fORM-control" id="companyid" v-model="couponSelected" @change='getCompanyId($event)'>
		<option v-for="(item,index) in data" v-bind:value=item.id>{{item.companyname}} 
        </option>
	  </select>
</div>

execFunc("company.getcompanylist", {}, function(result) {
		var vucom = new Vue({
			el : '#companylist',
			data : {
				data : []
			},
			created(){
               //默认值渲染必须
	           this.couponSelected = hcompanyid;
	        },
			methods : {
				getCompanyId : function(event) {
					$("#companyid").val(event.target.value);
				}
			}
		});
		vucom.data = result.data;
	})