element ui 时间选择器pickeroption里面this的指向问题

pickerOptions: {
        disabledDate(time) {
          console.log(this) //undefined 拿不到vue实例
          console.log(_this.searchForm.timeValue)//可以拿到值
          console.log(_this) //vue实例
          const lastYearDate = new Date(getLastFormatYear(time)).getTime()
          //  console.log(lastYearDate,8888)
          return time.getTime() > new Date() || time.getTime() < lastYearDate
        }
      }

data() {
    var _this = this
    return {
    .....
    }    

computed: {
    pickerOptions() {
      // 用计算属性
      let _this = this
      // 此时 this指向的就是vue实例
      return {
        disabledDate(time) {
          console.log(_this)//这里可以拿到this了
          return time.getTime() > Date.now()
        }
      }
    }
  }