求大神看下为啥2.3没有输出啊
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<script type="text/javascript">
function cl() {
alert('aaaaaaaaaaaaaaaaaaaaaaaaaaaaqq');
}
var n2=document.getElementById('n2');
var n3=document.getElementById('n3');
n2.onclick=function(){
alert('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');
}
n2.onclick=null;
var eventUtil={
addHandler:function(element,type,handler){
if(element.addEventListener){
element.addEventListener(type,handler,false);
}
else if(element.attachEvent){
element.attachEvent('on'+type,handler);
}
else{
element['on'+type]=handler;
}
}
}
eventUtil.addHandler(n3,'click',cl);
</script>
<div id="box1">
<input type="button" value="1" id="n1" onclick="cl()">
<input type="button" value="2" id="n2">
<input type="button" value="3" id="n3">
</div>
</body>
</html>
