JS正则表达式验证IP地址

var ip="255.255.255.255";alert(isIP(ip));alert(isIP2(ip));function isIP(ip){var reSpaceCheck = /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/;if (reSpaceCheck.test(ip)){ip.match(reSpaceCheck);if (RegExp.$1<=255&&RegExp.$1>=0  &&RegExp.$2<=255&&RegExp.$2>=0  &&RegExp.$3<=255&&RegExp.$3>=0  &&RegExp.$4<=255&&RegExp.$4>=0){return true; }else{return false;}}else{return false;}}function isIP2(ip) { var re =  /^(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])$/ return re.test(ip); }