/**  * Created by jwj on 2015/4/13.  * 增强Ext.panel.Panel(window,panel,form等界面组件)的beforeClose事件,以实现异步拦截  */ Ext.define('Ext.ux.overrides.panel.BeforeClose4async', {
      override: 'Ext.panel.Panel',     /**      * @event beforeclose      * 以实现异步拦截事件（beforeclose)      * @param this {Ext.panel.Panel}      * @param handlers {obj}      * @example      * listeners: {
       *   beforeClose: function (sender, handlers) {
       *       handlers.wait = true;      *       //注意这里只是做了个弹出窗口示例，ajax异步拦截关闭事件道理类似      *       Ext.MessageBox.confirm('提示：', '您确认要关闭此窗口吗？', function (btn) {
       *           if (btn === 'yes') {
       *               handlers.process();      *           } else {
       *               handlers.cancel();      *           }      *       });      *   }      *}      */     close: function () {
          /*if (this.fireEvent('beforeclose', this) !== false) {
           this.doClose();          }*/         var me = this,             handled = false,             handlers = {
                  wait: false,                 process: function () {
                      me.doClose();                     handled = true;                 },                 cancel: function () {
                      handled = true;                 }             },             performOperation = me.fireEvent('beforeclose', me, handlers);         if (handlers.wait) {
              return;         }         if (performOperation !== false) {
              if (!handled) {
                  handlers.process();             }         }         return performOperation;     } }); 备注：在Extjs5.1下测试通过，自定义异步拦截事件都可参照此例进行实现。