AB是兩個tab頁，切換的時候已經把addlist致為空數組了，js部分打印index值為啥是undefined？求解<div class="tit">區域編號 A</div>      <div class="item" v-for="item in addList" :key="item.index" v-if="addList.length>0">        <el-input v-model="item.shelves_number" disabled></el-input>        <el-input v-model="item.shelves_layer" disabled></el-input>        <el-input v-model="item.shelves_layer_num" disabled></el-input>        <span>{{item.shelves_num}}</span>        <span><button @click="delBtn_2(item.index,addList)">刪除</button></span> </div><div class="tit">區域編號 B</div>      <div class="item" v-for="item in addList" :key="item.index" v-if="addList.length>0">        <el-input v-model="item.shelves_number" disabled></el-input>        <el-input v-model="item.shelves_layer" disabled></el-input>        <el-input v-model="item.shelves_layer_num" disabled></el-input>        <span>{{item.shelves_num}}</span>        <span><button @click="delBtn_2(item.index,addList)">刪除</button></span> </div>js部分delBtn_2(index,data){       console.log(index);      data.splice(index,1);      this.setList.splice(index,1);