js正则表达式验证合法的IP地址

function isValidIP(ip) {
    var reg = /^(\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 reg.test(ip);
} 

let a = isValidIP('10.10.10.1111')
console.log(a)