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

执行没效果，想知道哪里错了？

<!DOCTYPE html>
<html xmlns="http://">
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8"></meta>     <!-- 可让中文正常显示 -->
    <title>鼠标滑过改变透明度</title>
    <link href="css/main.css" rel="stylesheet" />
    <style type="text/css">
    #div1{
        width: 200px;
        height: 200px;
        background: red;
        filter:alpha(opacity:30);
        opacity: 0.3;
    }
    </style>

    <script>
     window.onload=function(){
        var oDiv=document.getElementById('div1');
        oDiv.onmouseover=function(){
            startMove(100);
        }
        oDiv.onmouseout=function(){
            startMove(30);
     }

     var timer=null;
     var alpha=30;
     function startMove(iTarget){
         clearInterval(timer);
         var oDiv=document.getElementById('div1');      //再声明一次，因为不是全局变量
         timer=setInterval(function(){
            var speed=0;
            if (alpha>iTarget) {
                speed=-10;
            }
            else if（alpha<iTarget）{
                speed=10;
            }
            if (alpha==iTarget) {
                clearInterval(timer);
            }
            else{
                alpha+=speed;
                oDiv.style.filter='alpha(opacity:'+alpha+')';
                oDiv.style.opacity=alpha/100;         //火狐或者chrome浏览器才能正常显示
            }
         },30)
     }
    </script>

</head>

<body>
<div id="div1" ></div>
</body>
</html>

想知道我这代码哪里错了，在360浏览器和chrome都执行没效果啊，看不出来透明度变化