jQuery顶部浮动代码详解编程语言

<script type="text/javascript"> 
  var margintop = $("#header").offset().top 
  
  //var marginleft = $("#header_cont").offset().left; 
 //alert(margintop) 
 //alert(marginleft) 
   
   $(window).scroll(function() { 
     var scrtop = $(document).scrollTop(); 
     if(scrtop<margintop){ 
      $('#header').css({ 
          position: 'absolute', 
          top: margintop, 
          left:'0' 
        }); 
  
      return false; 
    } 
        $('#header').css({ 
          position: 'absolute', 
          top: scrtop, 
          left:'0' 
        }); 
    }); 
</script>