Extjs之window異步攔截關閉事件beforeClose的實現

/**
 * Created by jwj on 2015/4/13.
 * 增強Ext.panel.Panel(window,panel,form等界面組件)的beforeClose事件,以實現異步攔截
 */
Ext.define('Ext.ux.overrides.panel.BeforeClose4async', {
    override: 'Ext.panel.Panel',
    /**
     * @event beforeclose
     * 以實現異步攔截事件（beforeclose)
     * @param this {Ext.panel.Panel}
     * @param handlers {obj}
     * @example
     * listeners: {
     *   beforeClose: function (sender, handlers) {
     *       handlers.wait = true;
     *       //注意這里只是做了個彈出窗口示例，ajax異步攔截關閉事件道理類似
     *       Ext.MessageBox.confirm('提示：', '您確認要關閉此窗口嗎？', 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;
    }
});
備注：在Extjs5.1下測試通過，自定義異步攔截事件都可參照此例進行實現。