<!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>
<script language="javascript">
function xiansi(){
var arr =document.getElementById("members").value; //这是你要比较的值
//split()这是一个js函数在这里的作用是以 ‘ ’（空格为分隔符）分割成数组，arr的指就是保存1 1 2 2..的数值数组
var arr = arr.split("\n");
var nary=arr.sort();
for(var i=0;i<arr.length;i++){
if (nary[i]==nary[i+1]){
alert("数组重复内容："+nary[i]);
}
else{
var slt=document.getElementById("select");
var objOption=document.createElement("OPTION");
objOption.value=arr[i];
objOption.text=arr[i];
slt.add(objOption);
}
}
return false;
}
</script>
</head>
<body>
<form id="form1" name="form1" method="post" action="" onsubmit="javascript:return xiansi();">
<table width="100%" border="0" cellpadding="0" cellspacing="1">
<tr>
<td width="40%" height="167" bgcolor="#EBEBEB">
<label>
<div align="center">
<textarea id="members" name="textarea" rows="10" style="width:200px;"></textarea>
</div>
</label> </td>
<td width="20%" bgcolor="#EBEBEB"><div align="center">
<button id="checkleft">检查重复</button>
</div></td>
<td width="40%" bgcolor="#EBEBEB"><label>
<div align="center">
<select id="select" name="select" size="10" style="width:200px;">
</select>
</div>
</label></td>
</tr>
<tr>
<td height="30" colspan="3" bgcolor="#EBEBEB">
<div align="center">
<label>
<input type="submit" name="Submit" value="提交" />
</label>
</div> </td>
</tr>
</table>
</form>
</body>
</html>
js判断重复节点并增加节点的方法,布布扣,bubuko.com
原文：http://www.cnblogs.com/xiaonange/p/3581804.html