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;
}