                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /DOM事件探秘

为什么第三个按钮没有反应

<!DOCTYPE HTML>
<html>
<head>
<title>DOM</title>
<meta charset="utf-8">

</head>
<body>
   <div id="box">
   <input type="button" value="按钮" onclick="openWindow()" id="btn">
    <input type="button" value="按钮2" id="btn2">
     <input type="button" value="按钮3" id="btn3">
   </div>
   <script type="text/javascript">
   function openWindow()
   {
       alert("hi");
   }
   var btn2=document.getElementById("btn2");
   var btn3 =document.getElementById("btn3");
   btn2.onclick=function()
   {
       alert("你好");
   }
   btn3.addEventlistener("click",openWindow(),false);
   </script>
   </body>
</html>