表格动态合并，序号连续

效果：

 <el-table
      :data="tableData"
      style="width: 100%"
      v-loading="tableDataLoading"
      :header-cell-style="{ background: '#FAFAFA' }"
      :span-method="objectSpanMethod"
    >
　　　<el-table-column prop="mergeKey" label="序号" width="80">
        <template slot-scope="scope">
          <span>{{ scope.row.mergeKey + 1 }}</span>
        </template>
      </el-table-column>
 </el-table>

import { resoveData,  filterTable, trainMerge, } from "@/utils/util.js";

methods: {
    objectSpanMethod({ row, column, rowIndex, columnIndex }) {
      if ([0, 1, 2, 12, 13, 14].includes(columnIndex)) {
        let _row = this.rowspan[rowIndex]; // 合并的行
        let _col = this.rowspan[rowIndex] > 0 ? 1 : 0; // 1是开头0是被合并
        return [_row, _col];
      }
    },
   getList() {
      this.tableDataLoading = true;
      let params = {
        pageNum: this.listQuery.pageNum,
        pageSize: this.listQuery.pageSize,
        ...this.listQuery, // 参数
      };
      continuousRecordsPage(params).then((res) => {
        this.tableData = res.data.records;
        let newData = resoveData(res.data.records, "filingInfos");
        this.tableData = filterTable(newData);
        console.log(this.tableData);
        this.rowspan = trainMerge(newData, "mergeKey"); // 获取相同类型合并列的数据
        console.log(this.rowspan);
        this.total = res.data.total;
        this.tableDataLoading = false;
      });
    },  
}

util.js

//  把数据合并了进行拆解arr=>后台数据;arrKey=>合并数据的key
   export function resoveData(arr, arrKey, mergeKey = "mergeKey") {
     let newData = [];
     arr.forEach((item, index) => {
       // newData.push(item);
       item[arrKey].forEach(el => {
         newData.push({
           ...el,
           ...item,
           [mergeKey]: index,
         })
       })
     })
     return newData
   }
   // 格式化表格null的数据为 -
   export function filterTable(data) {
     if (!data) return [];
     data.forEach(item => {
       for (let key in item) {
         if (item[key] == null || item[key] === '') item[key] = '-';
       }
     })
     return data;
   }
   // 传入element表格需要合并相同列的key返回合并行组成的Array
   export function trainMerge(arr, key) {
     let rowspan = [];
     var obj = {},
       k;
     for (var i = 0, len = arr.length; i < len; i++) {
       k = arr[i][key]; //需要合并的字段
       if (obj[k]) obj[k]++;
       else obj[k] = 1;
     }
     console.log('===', obj);
     //保存结果{el-'元素'，count-出现次数}
     for (var o in obj) {
       for (let i = 0; i < obj[o]; i++) {
         if (i === 0) {
           rowspan.push(obj[o]);
         } else {
           rowspan.push(0);
         }
       }
     }
     return rowspan;
   }