element-ui table 表格组件合并相同行

    <template>
      <el-table
    :data="tableData"
    :span-method="objectSpanMethod"
    border
    style="width: 100%">
    <el-table-column
      prop="lv1"
      label="一级巡查项"/>
    <el-table-column
      prop="lv2"
      label="二级巡查项"/>
    <el-table-column
      prop="lv3"
      label="三级巡查内容描述"/>
    <el-table-column
      prop="lv4"
      label="三级巡查内容描述4"/>
    <el-table-column
      prop="lv5"
      label="三级巡查内容描述5"/>
    <el-table-column
      prop="lv6"
      label="三级巡查内容描述6"/>
      </el-table>
    </template>
    
    <script>
    export default {
      data() {
    return {
      tableData: [
        { lv1: '大坝', lv2: '堰顶', lv3: '堰顶是否平整', lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整' },
        { lv1: '大坝', lv2: '堰顶', lv3: '防浪墙是否平整' , lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整'},
        { lv1: '大坝', lv2: '堰顶', lv3: '两岸坝端是否危害', lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整' },
        { lv1: '大坝', lv2: '上游坝坡', lv3: '堰顶是否平整' , lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整'},
        { lv1: '大坝', lv2: '上游坝坡', lv3: '防浪墙是否平整' , lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整'},
        { lv1: '大坝', lv2: '上游坝坡', lv3: '两岸坝端是否危害', lv4: '堰顶是否平整', lv5: '堰顶是否平整', lv6: '堰顶是否平整' }
      ]
    }
      },
      methods: {
    objectSpanMethod({ row, column, rowIndex }) {
      const dataProvider = this.tableData
      const cellValue = row[column.property]
      if (cellValue) {
        // 上一条数据
        const prevRow = dataProvider[rowIndex - 1]
        // 下一条数据
        let nextRow = dataProvider[rowIndex + 1]
        // 当上一条数据等于下一条数据
        if (prevRow && prevRow[column.property] === cellValue) {
          return { rowspan: 0, colspan: 0 }
        } else {
          let rowspan = 1
          while (nextRow && nextRow[column.property] === cellValue) {
            rowspan++
            nextRow = dataProvider[rowspan + rowIndex]
          }
          if (rowspan > 1) {
            return { rowspan, colspan: 1 }
          }
        }
      }
    }
      }
    }
    </script>