<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>下拉菜单</title>
<style type="text/css">
body,ul,li{ margin:0; padding:0; font-size:13px;}
ul,li{list-style:none;}
#divselect{186px; margin:80px auto; position:relative; z-index:10000;}
#divselect cite{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{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],
as=box.getElementsByTagName('a'),
li = menu.getElementsByTagName('li'),
index=-1;
//鼠标移动背景颜色改变
for(var i=0;i<li.length;i++){
li[i].onmouseover = function() {
background(this, "red");
};
li[i].onmouseout = function(){
background(this,"white");
};
}
function background(obj,target){
obj.style.background = target;
}
//标题点击时触发的函数
title.onclick=function(event) {
menu.style.display = "block";
event.stopPropagation();//阻止冒泡事件
for (var i = 0; i < as.length; i++) {
as[i].onclick = function () {
title.innerHTML = this.innerHTML;
}
}
};
//键盘按键事件
//keyCode:回车键13，空格键32，向下方向键40，向上方向键38，向左方向键37，向右方向键39，shift键16，ctrl键17，alt键18
document.onkeyup = function(e){
if (e.keyCode == 40){
index++;
if (index >= as.length){//如果index的值大于等于了下拉框的长度，那么让index=as.length - 1
index = as.length - 1;
}
re()//这个函数的作用就是将所有的列的背景颜色变为白
as[index].style.backgroundColor="red";//然后这里又将按键按下的列的背景颜色更改为红色
}
if (e.keyCode == 38){
index--;
if (index< 0){
index= 0;
}
re();
as[index].style.backgroundColor="red";
}
if (e.keyCode== 13){
title.innerHTML = as[index].innerHTML;
menu.style.display = "none";
}
}
function re(){
for (var i= 0; i< as.length;i++){
as[i].style.backgroundColor = "#fff";
}
}
document.onclick = function(){
re();
menu.style.display = "none";
index = -1;
}
}
</script>
</head>
<body>
<div id="divselect">
<cite>请选择分类</cite>
<ul>
<li id="li"><a href="javascript:;" selectid="1">ASP开发</a></li>
<li><a href="javascript:;" selectid="2">.NET开发</a></li>
<li><a href="javascript:;" selectid="3">PHP开发</a></li>
<li><a href="javascript:;" selectid="4">Javascript开发</a></li>
<li><a href="javascript:;" selectid="5">Java特效</a></li>
</ul>
</div>
</body>
</html>