element下拉菜单默认选第一个

    gettimeStatus(dictType){
       changeStatus(dictType).then((response) => {
           switch (response.data.code) {
               case this.statusSuccess:
               // console.log('analysis_time_block', response.data)
               this.timeOption=response.data.result
               this.interval = this.timeOption[0].value;
               this.getreportList()
               break;
               default:
               this.msgError(response.data.code+'--'+response.data.msg);
               break;
           }
       })
   },

   <el-select v-model="interval"  @change="timechange($event)"  ref="interval" placeholder="时间间隔">
       <el-option
       v-for="item in timeOption"
       :key="item.id"
       :label="item.label"
       :value="item.value">
       </el-option>
   </el-select>