I got into trouble of this function, and I don't know what is the meaning of that:

menuItem1->setCallback([&](cocos2d::Ref *sender)

Enter the function, the param is ccMenuCallback&:

    /** set the callback to the menu item
    * @code
    * In js,can contain two params,the second param is jsptr
    * @endcode
    * @lua NA
    */
    void setCallback(const ccMenuCallback& callback);

And

typedef std::function<void(Ref*)> ccMenuCallback;