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

11111

h5.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
                });
           }