滚动时自动加载内容

var loading = false;
$(window).scroll(function(){
if((($(window).scrollTop()+$(window).height())+250)>=$(document).height()){
if(loading == false){
loading = true;
$('#loadingbar').css("display","block");
$.get("load.php?start="+$('#loaded_max').val(), function(loaded){
$('body').append(loaded);
$('#loaded_max').val(parseInt($('#loaded_max').val())+50);
$('#loadingbar').css("display","none");
loading = false;
});
}
}
});

$(document).ready(function() {
$('#loaded_max').val(50);
});