<!doctype html>
<html>
<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{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">
/**
* 下拉菜单
* @param {string} id 节点ID
*/
function Selecter (id) {
var parent = document.getElementById(id),
nodes = parent.children;
this.parent = parent;
this.title = nodes[0];
this.menu = nodes[1];
this.init();
}
/**
* 初始化
*/
Selecter.prototype.init = function(){
var doc = document;
this.selected = null;
this.maxLen = this.menu.children.length;
doc.addEventListener('click',this,false);
doc.addEventListener('keydown',this,false);
this.menu.addEventListener('mouseover',this,false);
this.menu.addEventListener('mouseout',this,false);
}
/**
* 事件处理
*/
Selecter.prototype.handleEvent = function(event){
var target = event.target || event.srcElement;
switch(target.nodeName){
//点击三角时
case 'CITE':
this.menuShow();
break;
// 滑过滑过、离开、点击每个选项时
case 'A':
this.removeLight();
this.selected = target;
this.menuUpdate();
this.hightLight();
if(event.type=='click'){
this.menuHide();
}
break;
// 点击页面空白处时
case 'HTML':
this.menuHide();
break;
//键盘操作
default:
this.keydown(event.keyCode);
break;
}
return
}
/**
* 更新菜单值
*/
Selecter.prototype.menuUpdate = function(){
this.title.innerHTML = this.selected.innerHTML;
}
/**
* 高亮选中项
*/
Selecter.prototype.hightLight = function(){
if(this.selected){
this.selected.style.backgroundColor = 'gray';
}
}
/**
* 移除高亮
*/
Selecter.prototype.removeLight = function(){
if(this.selected){
this.selected.style.backgroundColor = 'white';
}
}
/**
* 显示菜单项
*/
Selecter.prototype.menuShow = function(){
this.menu.style.display = 'block';
this.hightLight();
}
/**
* 隐藏菜单项
*/
Selecter.prototype.menuHide = function(){
this.menu.style.display = 'none';
}
/**
* 取下一项
*/
Selecter.prototype.next= function(){
var target = this.selected;
var index = target ? target.getAttribute('selectid')-1 : -1;
this.removeLight();
index = ++index % this.maxLen;
this.selected = this.menu.children[index].children[0];
this.hightLight();
}
/**
* 取上一项
*/
Selecter.prototype.prev = function(){
var target = this.selected;
var index = target ? target.getAttribute('selectid')-1 : 1;
this.removeLight();
index = --index < 0 ? 0 : index;
this.selected = this.menu.children[index].children[0];
this.hightLight();
}
/**
* 键盘操作
* @param {number} code ASSIC码
*/
Selecter.prototype.keydown = function(code){
switch(code){
case 40: //down
this.next();
break;
case 38://up
this.prev();
break;
case 13:
this.menuUpdate();
this.menuHide();
break;
default:
break;
}
}
window.onload=function(){
var menu = new Selecter('divselect');
}
</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>
