vue+elementui实现表格行合并

 getOrderNumber() {
        let OrderObj = {}
        this.tableData.forEach((element, index) => {
          element.rowIndex = index
          if (OrderObj[element.billType]) {
            OrderObj[element.billType].push(index)
          } else {
            OrderObj[element.billType] = []
            OrderObj[element.billType].push(index)
          }
        })

        // 将数组长度大于1的值 存储到this.OrderIndexArr（也就是需要合并的项）
        for (let k in OrderObj) {
          if (OrderObj[k].length > 1) {
            this.OrderIndexArr.push(OrderObj[k])
          }
        }
      },
       objectSpanMethod({row,column,rowIndex,columnIndex}) {
        if (columnIndex === 0 ) {
          for (let i = 0; i < this.OrderIndexArr.length; i++) {
            let element = this.OrderIndexArr[i]
            for (let j = 0; j < element.length; j++) {
              let item = element[j]
              if (rowIndex === item) {
                if (j === 0) {
                  return {
                    rowspan: element.length,
                    colspan: 1
                  }
                } else if (j !== 0) {
                  return {
                    rowspan: 0,
                    colspan: 0
                  }
                }
              }
            }
          }
        }
      },

data(){
	return{
			OrderIndexArr: [],
			tableData:[]
	}
}
<el-table ref="multipleTable" border :span-method="objectSpanMethod"
                v-loading="listLoading"
                :data="tableData">
</el-table> 
mounted(){
		获得数据后调用this.getOrderNumber()方法
}