为什么没人使用正则

```let str;
while(str=readline()){
    let flag = "YES";
    // ip port  reg : 
     let rr = /^((0)|(1\d{2})|(2[0-4]\d)|(25[0-5])|([1-9]\d?))\.((0)|(1\d{2})|(2[0-4]\d)|(25[0-5])|([1-9]\d?))\.((0)|(1\d{2})|(2[0-4]\d)|(25[0-5])|([1-9]\d?))\.((0)|(1\d{2})|(2[0-4]\d)|(25[0-5])|([1-9]\d?))$/
    print(rr.test(str) ? "YES" : "NO")
}