<!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>无标题文档</title>

</head>

<body>

<ul id="ul">

<li><a href="#">测试</a></li>

</ul>

<input type="button" value="增加" onclick="zeng()" />

<input type="button" value="减少" onclick="jian()" />

<script language="javascript" type="text/javascript">

<!--

var obj=document.getElementById("ul");

function zeng(){

        var liobj=document.createElement("li");

        var alink=document.createElement("a");          

        var message=document.createTextNode("测试");

             alink.appendChild(message);

        alink.href="#";

        liobj.appendChild(alink);

            obj.appendChild(liobj);

}

function jian(){

var linum=document.getElementById("ul").getElementsByTagName("li");

var length=parseInt(linum.length);

if(length==0){

  alert("不好意思,已经没有给你删的le");

}else{

  obj.removeChild(linum[0]);

}  

}  

//-->

</script>

</body>

</html>