html table动态合并单元格 js方法

<script>
$(document).ready(function(){
    function mc(tableId, startRow, endRow, col) {
        var tb = document.getElementById(tableId);
        if (col >= tb.rows[0].cells.length) {
            return;
        }
        if (col == 0) { endRow = tb.rows.length-1; }
        for (var i = startRow; i < endRow; i++) {
            if (tb.rows[startRow].cells[col].innerHTML == tb.rows[i + 1].cells[0].innerHTML) {
                tb.rows[i + 1].removeChild(tb.rows[i + 1].cells[0]);
                tb.rows[startRow].cells[col].rowSpan = (tb.rows[startRow].cells[col].rowSpan | 0) + 1;
                if (i == endRow - 1 && startRow != endRow) {
                    mc(tableId, startRow, endRow, col + 1);
                }
            } else {
                mc(tableId, startRow, i + 0, col + 1);
                startRow = i + 1;
            }
        }
    }
        mc('table1',0,0,0); 
    })
  </script>