                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /JS動畫效果

關于alpha>iTarget的問題想問下大家

<!doctype?html>
<html>
<head>
????<meta?charset="UTF-8">
<title>透明度</title>
<style>
*{
margin:0;padding:0;
}
#div{
width:300px;height:200px;background:red;filter:alpha(opacity:30);opacity:0.3;
}
</style>
????</head>
???<script>
???window.onload=function(){
???var?onDiv=document.getElementById('div');
???onDiv.onmouseover=function(){
??startmove(100);
??}
???onDiv.onmouseout=function(){
??startmove(30);
??}
??}
??var?timer=null;
??????alpha=30;
??function?startmove(iTarget){
var?onDiv=document.getElementById('div');
clearInterval(timer)
timer=setInterval(function(){
var?speed=0;
if(alpha>iTarget){
speed=-10;
}else{
speed=10;
}
if(alpha==iTarget){
clearInterval(timer);
}else{
alpha+=speed;
onDiv.style.filter='alpha(opacity:'+alpha+')';
onDiv.style.opacity=alpha/100;
}
},30)

}
???</script>
<body>
<p?id="div"></p>
</body>
</html>

老師在講alpha>iTarget我其實是有點懵的，因為我看了下已經定義了alpha=30，并且iTarget在30-100之間徘徊的，那我應該怎么去理解這句話？