var n = tab.getComponent(node.id);
                        if (!n) { //判断是否已经打开该面板
                            n = tab.add({
                                'id': node.id,
                                'title': '<center>' + node.text + '</center>',
                                closable: true,  //通过html载入目标页   
                                html: '<iframe scrolling="auto" frameborder="0" width="100%" height="100%" src="' + urlArray[node.id].url + '"></iframe>'
                            });
                        }
                        tab.setActiveTab(n);

如何在打开情况下就刷新一下里面的页面？急，谢谢了。