element table 合并单元格

	mergerItems: [
        { columnIndex: 0,
          spanArr: [],
          pos: 0,
          prop: 'index'
        },
        { columnIndex: 1,
          spanArr: [],
          pos: 0,
          prop: 'projectname'
        },
        { columnIndex: 2,
          spanArr: [],
          pos: 0,
          prop: 'bidprojectname'
        },
        { columnIndex: 3,
          spanArr: [],
          pos: 0,
          prop: 'constructdeptname'
        }
      ]
	// 表格合并的方法
    arraySpanMethod({ row, column, rowIndex, columnIndex }) {
      // const needMergeArray = [0, 1, 2, 3]
      const needMergeArray = [0, 1, 2, 3]

      if (needMergeArray.includes(columnIndex)) {
      // 这里判断第几列需要合并
        const item = this.mergerItems.find(item => {
          return item.columnIndex === columnIndex
        })

        const _row = item.spanArr[rowIndex]
        const _col = _row > 0 ? 1 : 0
        return {
          rowspan: _row,
          colspan: _col
        }
      }
    },
    // 循环数据处理
    getSpanArr(data, array) {
      for (let n = 0; n < array.length; n++) {
        array[n].spanArr = []// 数据清空(重新调此方法的时候需要清空上一次的数据)
        for (let i = 0; i < data.length; i++) {
          if (i === 0) {
            array[n].spanArr.push(1)
            array[n].pos = 0
          } else {
            // 判断当前元素与上一个元素是否相同
            if (data[i][array[n].prop] === data[i - 1][array[n].prop]) {
              array[n].spanArr[array[n].pos] += 1
              array[n].spanArr.push(0)
            } else {
              array[n].spanArr.push(1)
              array[n].pos = i
            }
          }
        }
      }
    }