$.ajaxSetup ({
    cache: false //关闭AJAX相应的缓存
});
var show_posts=function(){
	$.getJSON("/ajax/php/posts.php",function(json){
		$('#today_posts').html(json.today+"");
		$('#yesterday_posts').html(json.yesterday+"");
		setTimeout(show_posts,2000);
	});
}
show_posts();