JS实现左右列表动态添加及上下移动功能

完整HTML与JavaScript代码

<!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>
<title> new document </title>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
<meta name="author" content="" />
<meta name="keywords" content="" />
<meta name="description" content="" />
<link rel="stylesheet" type="text/css" href="" />
<style type="text/css"></style>
<script type="text/javascript"></script>
<META NAME="Description" CONTENT="Power by hill"> 
</head>
<body>
<p>选定一项或多项然后点击添加或移除(按住shift或ctrl可以多选)，或在选择项上双击进行添加和移除。</p> 
<form method="post" name="myform"> 
<table border="0" width="300"> 
<tr> 
<td width="40%"> 
<select style="WIDTH:100%" multiple name="list1" size="12" ondblclick="moveOption(document.myform.list1, document.myform.list2)"> 
<option value="北京">北京</option> 
<option value="上海">上海</option> 
<option value="山东">山东</option> 
<option value="安徽">安徽</option> 
<option value="重庆">重庆</option> 
<option value="福建">福建</option> 
<option value="甘肃">甘肃</option> 
<option value="广东">广东</option> 
<option value="广西">广西</option> 
<option value="贵州">贵州</option> 
<option value="海南">海南</option> 
<option value="河北">河北</option> 
<option value="黑龙江">黑龙江</option> 
</select> 
</td> 
<td width="20%" align="center"> 
<input type="button" value="添加" onclick="moveOption(document.myform.list1, document.myform.list2)">
<br/> 
<br/> 
<input type="button" value="删除" onclick="moveOption(document.myform.list2, document.myform.list1)"> 
</td> 
<td width="40%"> 
<select style="WIDTH:100%" multiple name="list2" size="12" ondblclick="moveOption(document.myform.list2, document.myform.list1)"> 
</select> 
</td> 
<td> 
<button onclick="changepos(list2,-1)" type="button">上移</button> 
<br/> 
<button onclick="changepos(list2,1)" type="button">下移</button> 
</td> 
</tr> 
</table> 
值：<input type="text" name="city" size="40"> 
</form> 
<script language="JavaScript"> 
function moveOption(e1, e2){ 
try{ 
for(var i=0;i<e1.options.length;i++){ 
if(e1.options[i].selected){ 
var e = e1.options[i]; 
e2.options.add(new Option(e.text, e.value)); 
e1.remove(i); 
ii=i-1 
} 
} 
document.myform.city.value=getvalue(document.myform.list2); 
} 
catch(e){} 
} 
function getvalue(geto){ 
var allvalue = ""; 
for(var i=0;i<geto.options.length;i++){ 
allvalue +=geto.options[i].value + ","; 
} 
return allvalue; 
} 
function changepos(obj,index) { 
if(index==-1){ 
if (obj.selectedIndex>0){ 
obj.options(obj.selectedIndex).swapNode(obj.options(obj.selectedIndex-1)) 
} 
} else if(index==1){ 
if (obj.selectedIndex<obj.options.length-1){ 
obj.options(obj.selectedIndex).swapNode(obj.options(obj.selectedIndex+1)) 
} 
} 
} 
</script> 
</body>
</html>