使用上下键进行完工数量这一列的切换

<el-table :data="form.detailList" @selection-change="handleChildSelection" ref="bChangeOrderChild" max-height="500">
 <!-- <el-table-column type="selection" width="50" align="center"/> -->
 <el-table-column label="序号" align="center" prop="index" width="50"/>

 <el-table-column label="产品名称">
   <template slot-scope="scope">
     <el-input v-model="scope.row.materialName" readonly/>
   </template>
 </el-table-column>
 <el-table-column label="完工数量" prop="wrastNum">
   <template slot-scope="scope">
     <el-input v-model="scope.row.wrastNum" placeholder="请输入完工数量" @focus="wrastNumFocus(scope.row)" @keyup.native="show($event,scope.$index)" class="table_input badY_input"/>
   </template>
 </el-table-column>
 <el-table-column label="入库批次号" prop="productBatchNum">
   <template slot-scope="scope">
     <el-input v-model="scope.row.productBatchNum" placeholder="请输入入库批次号" />
   </template>
 </el-table-column>
 <el-table-column label="开始时间" prop="planStartTime" width="230">
   <template slot-scope="scope">
     <el-date-picker clearable
       style="width: 100%;"
       v-model="scope.row.planStartTime"
       type="datetime"
       value-format="yyyy-MM-dd HH:mm:ss"
       placeholder="请选择开始时间">
     </el-date-picker>
   </template>
 </el-table-column>
 <el-table-column label="结束时间" prop="planEndTime" width="230">
   <template slot-scope="scope">
     <el-date-picker clearable
       style="width: 100%;"
       v-model="scope.row.planEndTime"
       type="datetime"
       value-format="yyyy-MM-dd HH:mm:ss"
       placeholder="请选择结束时间">
     </el-date-picker>
   </template>
 </el-table-column>
 <el-table-column label="备注" prop="note">
   <template slot-scope="scope">
     <el-input v-model="scope.row.note" placeholder="请输入备注" />
   </template>
 </el-table-column>
</el-table>

//键盘触发事件
show(ev,index){
  let newIndex;
  let inputAll = document.querySelectorAll('.table_input input');

  //向上 =38
  if (ev.keyCode == 38) {

    if( index==0 ) {// 如果是第一行,回到最后一个
      newIndex = inputAll.length - 1
    }else if( index == inputAll.length ) {// 如果是最后一行，继续向上
      newIndex = index - 1
    }else if( index > 0 && index < inputAll.length ) {// 如果是中间行，继续向上
      newIndex = index - 1
    }

    if (inputAll[newIndex]) {
      inputAll[newIndex].focus();
    }
  }

  //下 = 40
  if (ev.keyCode == 40) {

    if( index==0 ) {// 如果是第一行,继续向下
      newIndex = index+1
    }else if( index == inputAll.length-1 ) {// 如果是最后一行，回到第一个
      newIndex = 0
    }else if( index > 0 && index < inputAll.length ) {// 如果是中间行，继续向下
      newIndex = index + 1
    }

    if (inputAll[newIndex]) {
      inputAll[newIndex].focus();
    }
  }
}