关于elementUi表格合并行数据并展示序号

    <base-table
      :table-data="tableData"
      :table-title="tableTitle"
      :span-method="objectSpanMethod"
      max-height="600px"
      v-bind="$attrs"
    >
      <template slot-scope="scope" slot="serialNo">
        {{ scope.row.serialNo }}
      </template>
      ....
    </base-table>

const tableTitle = [
  {
    key: 'serialNo',
    title: '序号',
    align: 'center',
    width: '100',
    scopedSlots: { customRender: 'serialNo' }
  },
  {
    key: 'unionList',
    title: '厂商名称(编号)',
    align: 'center',
    width: '300px',
    scopedSlots: { customRender: 'unionList' }
  },
  {
    key: 'unionName',
    title: 'MQ厂商',
    tooltip: true,
    align: 'center'
  },
]
export default {
  data() {
    return {
      tableTitle,
      tableData: [],
      spanArr: [], // 存合并行数据的数组
      pos: 0,// 合并行数据数组下标
      rowIndex: 1 // 序号
    }
  },

  methods: {
    getTableData() {
      this.tableData = [
        {
          accessId: '1',
          id: 1,
          mqPassword: '1011',
          privateKey: '1011',
          publicKey: '1011',
          unionList: "[{\"union_name\":\"乐乐\",\"union_id\":\"200160\"}]",
          unionName: '1011'
        },
        {
          accessId: '2',
          id: 2,
          mqPassword: '1012',
          privateKey: '1012',
          publicKey: '1012',
          unionList: "[{\"union_name\":\"小太阳\",\"union_id\":\"200734\"},{\"union_name\":\"包子\",\"union_id\":\"200737\"}]",
          unionName: '1012'
        },
        {
          accessId: '3',
          id: 3,
          mqPassword: '1013',
          privateKey: '1013',
          publicKey: '1013',
          unionList: "[{\"union_name\":\"小太阳\",\"union_id\":\"200734\"},{\"union_name\":\"包子\",\"union_id\":\"200737\"}]",
          unionName: '1013'
        },
        {
          accessId: '4',
          id: 4,
          mqPassword: '1014',
          privateKey: '1014',
          publicKey: '1014',
          unionList: "[{\"union_name\":\"测试\",\"union_id\":\"200160\"}]",
          unionName: '1014'
        },
      ]
      this.getSpanArr(this.tableData) // 获取合并单元格数据和序号
    },
    getSpanArr(data) {
    // 重新查询后，要清空行数据数组、序号重置为1
      this.spanArr = []
      this.rowIndex = 1
      // 遍历数据，判断前后两条数据是否相同
      for (let i = 0; i < data.length; i++) {
        data[i].unionList = JSON.parse(data[i].unionList)
        data[i].unionArr = data[i].unionList.map(i => i.union_id).join(',')
        if (i === 0) {
          this.spanArr.push(1)
          this.pos = 0
          data[i].serialNo = this.rowIndex
          this.rowIndex++
        } else {
          // 判断当前元素与上一元素是否相同
          if (data[i].unionArr === data[i - 1].unionArr) {
            this.spanArr[this.pos] += 1
            this.spanArr.push(0)
          } else {
            this.spanArr.push(1)
            this.pos = i
            data[i].serialNo = this.rowIndex
            this.rowIndex ++
          }
        }
      }
    },
    objectSpanMethod({ row, column, rowIndex, columnIndex }) {
      // 合并操作和厂商名称
      if (columnIndex === 0 || columnIndex === 1 || columnIndex === 2) {
        const _row = this.spanArr[rowIndex]
        const _col = _row > 0 ? 1 : 0
        // rowspan和colspan都为0，则表示这一行不显示，[x, 1]则表示合并了多少行
        return {
          rowspan: _row,
          colspan: _col
        }
      }
    },
  }
}