javascript中判断IP地址格式

function checkIp(ip){      
var ipPattern = new RegExp(      
         "^(([1-9][0-9]?)|(1[0-9]{2})|(2[0-4][0-9])|(25[0-5]))\\.      
           ((0)|([1-9][0-9]?)|(1[0-9]{2})|(2[0-4][0-9])|(25[0-5]))\\.      
           ((0)|([1-9][0-9]?)|(1[0-9]{2})|(2[0-4][0-9])|(25[0-5]))\\.      
           ((0)|([1-9][0-9]?)|(1[0-9]{2})|(2[0-4][0-9])|(25[0-5]))$","g");      

var ip6Pattern=new RegExp(      
        "^(^::$)      
         |(^([\\d|a-fA-F]{1,4}:){7}([\\d|a-fA-F]{1,4})$)      
         |(^(::(([\\d|a-fA-F]{1,4}):){0,5}([\\d|a-fA-F]{1,4}))$)      
         |(^(([\\d|a-fA-F]{1,4})(:|::)){0,6}([\\d|a-fA-F]{1,4})$)$","g");      

if(ipPattern.test(ip)){      
return true;      
}      
        if (ip6Pattern.test(ip)){      
          var pos=ip.indexOf("::");      
                 if (pos>-1)      
                 {      
                        pos=ip.indexOf("::",pos+2);      
                        if (pos>-1) return false;      
                 }      
   return true;      
        }      
return false;      
}