Jquery Flexslider添加并移除幻灯片上的类。

I'm using the jquery plugin Flexslider. I'm using the carousel as navigation for the slider. I'm trying to add a css class "active" to the first carousel element when the page loads, then remove the "active" class from the first element as the user chooses another element and add the "active" class to the next element the user chooses. . I'm usi