上拉加载jq

 //下拉加载用户数据
    var a = 0;
    var offsize = 6;//起始位置(查询数据表时的起始位置)
    $(document).ready(function(){
        var range = 80;//距下边界长度/单位px
        var totalheight = 0;
        var main = $("#loadinguser");//主体元素
        $(window).scroll(function(){
            var srollPos = $(window).scrollTop();
            totalheight = parseFloat($(window).height()) + parseFloat(srollPos);
            if(($(document).height()-range) <= totalheight) {
                if(a==0)
                {
                    a = 1;
                    $('#loading').html("正在努力为您加载...");
                    $.post("{:url('index2NextPage')}",{
                        offsize:offsize,
                        tid:{$ppid},
                    },function(data){

                        if(data==0)
                        {
                            $('#loading').html("已为您加载全部");
                            a = 0;
                        }
                        else
                        {
                            main.append(data);
                            offsize = offsize+6;
                            a = 0;
                        }
                    });
                }
            }
            //获取图片的高放在文字上
    	var imgHeight=$('.dyimg img').height()
    	var headerHeight=$('.plinfos').height()
    	var imgRem=imgHeight-headerHeight
    	$(".plinfos ").css('top',imgRem+'px')
        });
    });