IP验证

function isIP(str) {
    var IP = '(25[0-5]|2[0-4]\\d|1\\d\\d|\\d\\d|\\d)';
    var IPdot = IP + '\\.';
    var isIPaddress = new RegExp('^' + IPdot + IPdot + IPdot + IP + '$');
    return (isIPaddress.test(str));
}