滚动页面到顶部的动画

 
 <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js"></script>  
  <script>  $(document).ready(function(){            
// hide #back-top first          
$("#back-top").hide();                    
// fade in #back-top          
$(function () {                  
$(window).scroll(function () {                          
if ($(this).scrollTop() > 100) {                                  
$('#back-top').fadeIn();                          
} else {                                  
$('#back-top').fadeOut();                          
}                  
});                    
// scroll body to 0px on click                  
$('#back-top a').click(function () {                          
$('body,html').animate({                                  
scrollTop: 0                          
}, 800);                          
return false;                  
});          
});    
});  </script>  

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