What should I do if the Vue reference datepicker plug-in cannot monitor the value of the datepicker input box?

 <label class="fl">日期：</label>
 <p class="input-wrapper fr">
  <input class="daterangepicker" ref="datepicker" v-model="dateRange"/>
  <a href="javascript:;" rel="external nofollow" ></a>
 </p>
export default {
  data() {
    return {
      dateRange: &#39;&#39;
    }
  },
  watch: {
    dateRange(newVal, oldVal) {
      console.log(newVal) // 选择日期后无法监听dateRange的改变
    }
  }
}

data() {
    return {
      date: '',
      beginDate: '',
      endDate: ''
    }
  },
mounted () {
  $('.daterangepicker').dateRangePicker({
    autoClose: true,
    format: 'YYYY-MM-DD'
  }).bind('datepicker-change', this.setDate) //插件自带方法，选择日期后触发回调
 },
methods: {
  setDate() {
    let datepicker = this.$refs.datepicker
    //这一步是关键，具体说明可以参见vue api手册
    this.$set(this.date, 'beginDate', datepicker.value)
    this.$set(this.date, 'endDate', datepicker.value)
    this.beginDate = this.date.beginDate.slice(0, 11)
    this.endDate = this.date.endDate.slice(-10)
  }  
 },
  watch: {
  // 这里就可以监听数据变化啦，可以愉快的选择日期了！
   beginDate(newVal, oldVal) {
     this.$emit( 'beginDateChange', newVal )
   },
   endDate(newVal, oldVal) {
     this.$emit( 'endDateChange', newVal )
   }
  }