JS方式检验输入的IP

//IP设置的判断 只能数字和0
function IpreturnSetSubmit(){
var ip=getid("system_ip").value;
var mask=getid("system_mask").value;
var way=getid("system_way").value;
var reg = /^(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])$/
if((reg.test(system_ip)==false) || (reg.test(system_mask)==false) || (reg.test(system_way)==false))
{
alert("输入格式有误！");
return false;
}
alert("已发送!");
return true;
}