js 动态合并单元格并求和

function autoRowSpan(tb, row, col) {  
            var lastValue = "";  
            var value = "";  
            var pos = 1;  
            var tdSum = 0;  
            var cellValue = 0;  
            for (var i = row; i < tb.rows.length; i++) {  
                value = tb.rows[i].cells[col].innerText;  
                if (lastValue == value) {//判断产品名称是否相同  
                    if (!isNaN(tb.rows[i].cells[4].innerText))//判断是否为数字类型  
                    cellValue =cellValue+ parseFloat(tb.rows[i].cells[4].innerText);  
                    tb.rows[i].deleteCell(col);  
                    tb.rows[i - pos].cells[col].rowSpan = tb.rows[i - pos].cells[col].rowSpan + 1;//设置单元格rowSpan的值  
                    var z = tb.rows(i).cells.length;  
                    tb.rows[i].deleteCell(z - 1);  
                    tb.rows[i - pos].cells[z].rowSpan = tb.rows[i - pos].cells[z].rowSpan + 1//合并标煤合计那一列的单元格  
                    tb.rows[i - pos].cells[5].innerText = cellValue;//进行复制  
                    pos++;  
                } else {//产品名称不同的处理  
                    lastValue = value;  
                    cellValue = parseFloat(tb.rows[i].cells[4].innerText);  
                    if (!isNaN(cellValue))  
                        tb.rows[i].cells[5].innerText = cellValue;  
                    pos = 1;  
                    tdSum = 0;  
                }  
            }  
        }