组件式web app 开发中，每页添加底层图片的过程不是很清楚，就是whenAddPage，求前辈指点

Question

11111h5.whenAddPage = function(){                 this.addComponent('slide_up',{                     bg:'imgs/footer.png',                     css:{                         opacity:0,                         left:0,                         bottom:-20,                         width:'100%',                         height:'20px',                         zIndex:999                     },                     animateIn:{opacity:1,bottom:'-1px'},                     animateOut:{opacity:0,bottom:'-20px'},                     delay:500                 });            }