var stop=true;
$(window).scroll(function(){
    totalheight = parseFloat($(window).height()) + parseFloat($(window).scrollTop());
    if($(document).height() <= totalheight){
        if(stop==true){
            stop=false;
            //下滑到底后要执行的代码


            stop=true;
        }
    }
});

js实现下滑加载更多的效果