                        課程
                    
                        /前端開發(fā)
                        
                            /JavaScript
                        
                        /DOM事件探秘

只能寫成這樣了，改了好長時(shí)間

<!DOCTYPE html>
<html>
<head>
??? <meta charset="UTF-8">
??? <title>下拉菜單</title>
?<style type="text/css">
body,ul,li{ margin:0; padding:0; font-size:13px;}
ul,li{list-style:none;}
#divselect{width:186px; margin:80px auto; position:relative; z-index:10000;}
#divselect cite{width:150px; height:24px;line-height:24px; display:block; color:#807a62; cursor:pointer;font-style:normal;
padding-left:4px; padding-right:30px; border:1px solid #333333;
background:url(xjt.png) no-repeat right center;}
#divselect ul{width:184px;border:1px solid #333333; background-color:#ffffff; position:absolute; z-index:20000; margin-top:-1px; display:none;}
#divselect ul li{height:24px; line-height:24px;}
#divselect ul li a{display:block; height:24px; color:#333333; text-decoration:none; padding-left:10px; padding-right:10px;}
?</style>
?? <script type="text/javascript">
window.onload=function(){
?var box=document.getElementById('divselect'),
???? title=box.getElementsByTagName('cite')[0],
???? menu=box.getElementsByTagName('ul')[0],
???? lis=menu.getElementsByTagName('li');
???? as=box.getElementsByTagName('a'),
??????? index=-1;
??
??? // 點(diǎn)擊三角時(shí)
??? title.onclick=function(event){
????? // 執(zhí)行腳本
?????
????? if(index>=0){

??????? as[index].style.background="#ccc";
????? }
????? e=event||window.event;
????? if(e.stopPropagation){
????? ?e.stopPropagation();
????? }else{
????? ?e.cancelBubble=true;
????? }
????? menu.style.display="block";//阻止冒泡
?? }
?? // 滑過滑過、離開、點(diǎn)擊每個(gè)選項(xiàng)時(shí)
?? for (var i=0,l=as.length;i<l;i++) {
?? ?? as[i].onmouseover=function(){
?? ?? ?this.style.background='#ccc';
?? ?? }
?? ?? as[i].onmouseout=function(){
?? ?? ?this.style.background='#fff';
?? ?? }
?? ?? as[i].onclick=function(event){
????????? e=event||window.event;//兼容性
????????? if(e.stopPropagation){
??????????? e.stopPropagation();
????????? }else{
????? ???? e.cancelBubble=true;
????????? }??
????????? title.innerHTML=this.innerHTML;
????????? menu.style.display="none";
??????? }
?? } ????? // 執(zhí)行腳本
?? // 點(diǎn)擊頁面空白處時(shí)
?????? // 執(zhí)行腳本
? document.onclick=function(){
? ?menu.style.display="none";
? }
? //鍵盤事件
? document.onkeyup=function(event){
? ?for(var i=0,l=as.length;i<l;i++){
? ??as[i].style.background="#fff";
? ?}
? ?event=event||window.event;
? ?event=event.keyCode;
? ?if(event==38){//按下上鍵
????? --index;
????? if(index<0){index=as.length-1;}
????? as[index].style.background='#ccc';
? ?}else if(event==40){//按下下鍵
????? ++index;
????? if(index>=as.length){
???????? index=0;
????? }
????? as[index].style.background="#ccc";
? ?}else if(event==13){
????? title.innerHTML=as[index].innerHTML;
????? menu.style.display="none";
? ?}
? }
}
?? </script>
</head>
<body>
?<div id="divselect">
????? <cite>請(qǐng)選擇分類</cite>
????? <ul>
???????? <li id="li"><a href="javascript:;" selectid="1">ASP開發(fā)</a></li>
???????? <li><a href="javascript:;" selectid="2">.NET開發(fā)</a></li>
???????? <li><a href="javascript:;" selectid="3">PHP開發(fā)</a></li>
???????? <li><a href="javascript:;" selectid="4">Javascript開發(fā)</a></li>
???????? <li><a href="javascript:;" selectid="5">Java特效</a></li>
????? </ul>
??? </div>
</body>
</html>