利用javascirpt我们可以很容易的在HTML中实现树，而不需要使用ASP,JSP,PHP等等编写动态程序，当然如果要和数据库结合，下面的代码也很容易移植。
首先，我们看一下实现这个树形结构的javascript代码。
common.js
<!--
function showCurrentSection()
{
var objCurrentSection = document.getElementById("navcurrentsection");
if (objCurrentSection != null)
{
objCurrentSection.style.display = "block";
objCurrentSection.parentElement.childNodes[0].className = "open";
if (objCurrentSection.parentElement.parentElement.nodeName == "UL")
showSection(objCurrentSection.parentElement.parentElement);
}
}
function showSection(objSection)
{
objSection.style.display = "block";
objSection.parentElement.childNodes[0].className = "open";
if (objSection.parentElement.parentElement != null && objSection.parentElement.parentElement.nodeName == "UL")
showSection(objSection.parentElement.parentElement);
}
-->
下面是实现树的静态HTML文件，很简单的啊。
example1.html
<!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" xml:lang="en" lang="en">
<head>
<title>Current Tree Node Opener</title>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<link rel="stylesheet" href="tree.css" type="text/css" media="screen" />
<meta http-equiv="expires" content="-1" />
<meta http-equiv="pragma" content="no-cache" />
<meta name="robots" content="none" />
<meta name="rating" content="all" />
<meta name="author" content="Bluegrass Technologies" />
<meta name="email" content="paulw@bluegrassgroup.com" />
<script language="javascript" type="text/javascript" src="common.js"></script>
</head>
<body onload="showCurrentSection();">
<ul id="menu">
<li><a href="a.htm">Section 1</a></li>
<li><a href="">Section 2</a>
<ul>
<li><a href="">Section 2.1</a></li>
<li><a href="">Section 2.2</a></li>
<li><a href="">Section 2.3</a>
<ul id="navcurrentsection">
<li><a href="">Section 2.3.1</a></li>
<li><a href="">Section 2.3.2</a></li>
</ul>
</li>
<li><a href="">Section 2.4</a></li>
</ul>
</li>
<li><a href="">Section 3</a></li>
</ul>
</body>
</html>
下面是树的样式表
tree.css
body
{
font-family: Verdana, Arial, Sans-Serif;
font-size: small;
background-color: #ffffff;
}
ul#menu
{
border: solid 1px #333333;
border-top-width: 15px;
padding: 10px;
padding-top: 6px;
margin: 0px;
width: 200px;
}
ul#menu li
{
margin: 0px;
list-style-type: none;
border: solid 1px #ffffff;
}
ul#menu li ul
{
margin: 0px 0px 0px 15px;
display: none;
}
ul#menu li a
{
background-image: url(closed.gif);
background-repeat: no-repeat;
background-position: 0px 4px;
text-indent: 15px;
display: block;
text-decoration: none;
color: #333333;
}
ul#menu li a:hover
{
color: #000000;
background-color: #eeeeee;
background-image: url(open.gif);
}
好了，到这里为止，我们已经实现了这个树，大家不妨亲自演示一下。