为什么跨浏览器事件处理程序不能执行？

<!DOCTYPE html>
<html>
<head>
   <title>20160217</title>
</head>
<body>
   <input type="button" value="按钮" id="btn">
   <script type="text/javascript">
   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;
        }
    }
    removeHandler:function (element,type,handler){
        if (element.removeEventListener){
            element.removeEventListener(type,handler,false);
        }else if(element.detachEvent){
            element.detachEvent("on"+type,handler);
        }else {
            element["on"+type]=null;
        }
    }
   }
   var btn=document.getElementById("btn");
   eventUtil.addHandler(btn,"click",show);
   function show(){
    alert("hello");
   }
   </script>
</body>
</html>

wanoneQ

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1回答

李晓健

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