                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /JS动画效果

麻烦大家帮忙看看代码的错误！谢谢了

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<style type="text/css">
/*body,div{margin:0 padding:0}*/
#div1{ height:200px;
       width:200px;
	  background:#F00;
	  filter:alpha(opacity:30);
      opacity:0.3;
	  
   }
</style>
<script type="text/javascript">
window.onlond = function(){
var div1=document.getElementById('div1');
 div1.onmouseover=function(){
 	change(100);
 	}
 div1.onmouseout=function(){
	 change(30);
    }
	}	
	var timer=null;
	var alpha=30;
	function change(e){
	var div1=document.getElementById('div1');
	clearInterval(timer);
			var speed=0;
	timer=setInterval(function(){
		if(alpha>e){
			speed=-10;
		}
		else{
		    speed=10;	
		}
		if(alpha == e){
		clearInterval(timer);
		}
		else{
		alpha+=speed;
		div1.style.filter ='alpha(opacity:'+alpha+')' ;
		div1.style.opacity = alpha/100;
		}
	},30)
		
	}
	
</script>
<body>
<div id="div1"></div>
</body>
</html>