Extjs grid 合并单元格

/*
这个方法四个参数分别是
row:合并起始行
col:合并起始列.这两个参数是为了定位,要从哪个单元格开始合并.
type:是要合并行或者列.
num:是要合并的数量

//==>监听load , 执行合并单元格
grid.getStore().on('load', function () {
span(grid, 0, 0, 'row', 5);
});
*/
var span = function (grid, row, col, type, num) {
    switch (type) {
        case 'row':
            tds = Ext.get(grid.view.getNode(row)).query('td');
            Ext.get(tds[col]).set({ rowspan: num });
            Ext.get(Ext.get(tds[col])).setStyle({ 'vertical-align': 'middle' });
            for (i = row + 1; i < row + num; i++) {
                Ext.get(Ext.get(grid.view.getNode(i)).query('td')[col]).destroy();
            }
            break;
        case 'col':
            tds = Ext.get(grid.view.lockedView.getNode(row)).query('td');
            Ext.get(tds[col]).set({ colspan: num });
            break;
    }
};