JS常用正则表达式

var reg = /^(([1-9])|([1-9][0-9])|(1[0-9][0-9])|(2[0-4][0-9])|(25[0-5]))\.(([0-9])|([1-9][0-9])|(1[0-9][0-9])|(2[0-4][0-9])|(25[0-5]))\.(([0-9])|([1-9][0-9])|(1[0-9][0-9])|(2[0-4][0-9])|(25[0-5]))\.(([0-9])|([1-9][0-9])|(1[0-9][0-9])|(2[0-4][0-9])|(25[0-5]))$/;
var ip = "192.168.30.254";
var flag = ip.match(reg) == null ? false : true;
alert(flag);