大神能不能帮看下到底代码哪儿出问题了?

<!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>
<style>
*{ margin:0; padding:0;}
#first{ width:200px;
        height:200px;
        background: #0F0;
        filter:alpha(opacity:30);
        opacity:0.3;}
</style>
<script>
window.onload=function(){
 var block=document.getElementById('first');
   block.onmouseover=function(){
      change(100); 
       }
    block.onmouseout=function(){
        
      change(30); 
       }           
}//onload
var timer=null;
var alpha=30;
function change(target){
  clearInterval(timer);
  var block=document.getElementById('first');
  var speed=0;
   setInterval(function(){
    if(alpha>target){
     speed = -1;
     }else{
     speed = 1;
     }
     if(alpha==target){
    clearInterval(timer);     
     }else{
    alpha+=speed
    block.style.filter='alpha(opacity:'+alpha+')' ;
    block.style.opacity=alpha/100; }  },30); 
      
}


</script>
</head>

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


Dangui
浏览 1112回答 1
1回答

_潇潇暮雨

第32行应该是timer = setInterval();你之前的定时器没有清除。
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JavaScript