ant select有默認值但是還顯示placeholder

將默認值設置為空數組

<a-select placeholder="請選擇入學年份"
        :defaultValue="chooseGrade"
        @change="handleChange"
        @pressEnter="check">
<a-select-option v-for="items in grades"
                 :key="items.value"
                 :value="items.valueDisplay">{{items.valueDisplay}}</a-select-option>
</a-select>

js
data () {
    return {
      chooseGrade: []
    }
  }