extjs2.2 combo的监听

listeners : {
beforeselect : function(combo) {
prov = combo.getValue();
},
select : function(combo, record, index) {
if (prov != combo.getValue()) {
var area = Ext.getCmp('areano');
var county = Ext.getCmp("countyno");
areaStore.removeAll();
countyStore.removeAll();
areaStore.baseParams.provinceno = combo.getValue();
areaStore.load();
area.setValue("");
area.setRawValue("");
county.setValue("");
county.setRawValue("");
}
}
}