我正在构建一个绑定(bind)到$(window).scroll()事件的自动跟随div。这是我的JavaScript。varalert_top=0;varalert_margin_top=0;$(function(){alert_top=$("#ActionBox").offset().top;alert_margin_top=parseInt($("#ActionBox").css("margin-top"));$(window).scroll(function(){varscroll_top=$(window).scrollTop();if(scroll_top>alert_to