                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /DOM事件探秘

和源碼差不多，怎么就是實現不了效果

<!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=gb2312"?/>
	<title>Document</title>
	<style>
	?*{margin:0;padding:0;}
?????.head{font-size:12px;padding:6px?0?0?10px;}
?????#login_box{width:300px;height:150px;background:#eee;
?????border:1px?solid?#ccc;position:absolute;left:50%;top:50%;margin-left:-150px;margin-top:-75px;display:none;}
?????#login_box?p{height:20px;border-bottom:1px?solid?#ccc;font-size:12px;padding:6px?0?0?5px;font-weight:bold;}
?????#close{width:14px;height:14px;background:url(close.png)?no-repeat;position:absolute;right:4px;top:6px;}
	</style>
	<script>
??????window.onload=function(){
??????	var?login_btn=document.getElementById('login'),
??????	????login_box=document.getElementById('login_box'),
??????	????close=document.getElementById('close');
??????	//?封裝添加事件監聽程序
????????function?addEvent(ele,type,hander){
???????????if(ele.addEventListener){
???????????????ele.addEventListener(type,hander,false);
???????????????
???????????}else?if(ele.attachEvent){
???????????????
???????????????ele.attachEvent('on'+type,hander);
???????????}else{
???????????????
???????????????ele['on'+type]=hander;
???????????}
??????	}
????????//?顯示登錄層函數
??????	function?showLogin(){
??????	????//?執行代碼
??????????????login_box.style.display='black';
????????}
????????//?隱藏登錄層函數
????????function?hideLogin(){
??????????//?執行代碼
??????????????login_box.style.display='none';
????????}
????????//點擊登錄按鈕顯示登錄層?
????????//?執行代碼
???????/?addEvent(login_btn,'click',showLogin);
????????//點擊關閉按鈕隱藏登錄層
????????//?執行代碼
????????addEvent(close,'click',hideLogin);
??????}
	</script>
</head>
<body>
	<div?class="head">親，您好！<input?type="button"?value="登?錄"?id="login"></div>
	<div?id="login_box">
		<p>用戶登錄</p><span?id="close"></span>
	</div>
</body>
</html>