select转combobox的extjs代码

Ext.onReady(function(){
           Ext.QuickTips.init();
           storeList = new Ext.form.ComboBox({   
                 typeAhead: true,
                 triggerAction: 'all',
                 emptyText:'---请选择---',
                 mode: 'local',
                 electOnFocus:true,
                 transform:'selectTagId',    
                 width:250
           });
   })