校验IP地址是否合法,JavaScript

<script language="JavaScript">
<!--
/*
函数名: chkIP
功  能: 校验IP地址是否合法,并检查IP地址类型.
参  数: ###.###.###.### 格式的IP字符串
返回值: 整数,意义见注释
日  期: 2006-7-19
作  者: 梅雪香(meixx)
*/
function chkIP(ipStr){
//参数格式校验 成功继续,失败返回-1
ipStr = ipStr.replace(/\s/g,"");
var reg = /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/;
if(reg.test(ipStr) == false){
return -1;
}
//ip地址合法性校验 成功继续 ,失败返回-2
var arr = ipStr.split(".");
for(var i=0;i<4;i++){
arr[i] = parseInt(arr[i],10);
if(parseInt(arr[i],10) > 255)
return -2;
}
var ip = arr.join(".");
//返回IP地址的类型 包括:
//异常:0 A类:1 B类:2 C类:3 D类:4 E类:5 A类私有:6 B类私有:7 C类私有:8 本机IP:9 广播地址:10
//A类子网掩码:11 B类子网掩码:12 C类子网掩码:13
var retVal = 0;
var n = arr[0];

if(ip == "255.255.255.255")retVal = 10;
else if(ip == "255.255.255.0" ) retVal = 13;
else if(ip == "255.255.0.0") retVal = 12;
else if(ip == "255.0.0.0") retVal = 11;
else if(ip == "0.0.0.0" || ip == "127.0.0.1") retVal = 9;
else if(n <= 126)retVal = (n == 10 ? 6 : 1);
else if(n <= 191)retVal = (n == 172 ? 7 : 2);
else if(n <= 223)retVal = (n == 192 ? 8 : 3);
else if(n <= 239)retVal = 4;
else if(n <= 255)retVal = 5;
else ;
return retVal;
}
document.write(chkIP("11.65.96.1") + "<br/>");
document.write(chkIP("130.65.96.1") + "<br/>");
document.write(chkIP("210.65.96.1") + "<br/>");
document.write(chkIP("234.65.96.1") + "<br/>");
document.write(chkIP("251.65.96.1") + "<br/>");
document.write(chkIP("10.65.96.1") + "<br/>");
document.write(chkIP("172.65.96.1") + "<br/>");
document.write(chkIP("192.65.96.1") + "<br/>");
document.write(chkIP("0.0.0.0") + "<br/>");
document.write(chkIP("127.0.0.1") + "<br/>");
document.write(chkIP("255.255.255.255") + "<br/>");
document.write(chkIP("255.0.0.0") + "<br/>");
document.write(chkIP("255.255.0.0") + "<br/>");
document.write(chkIP("255.255.255.0") + "<br/>");
document.write(chkIP("255.255.256.0") + "<br/>");
document.write(chkIP("255.sd5.256.0") + "<br/>");
//-->
</script>