Validator (npm) Username Validation

Question

I am building a web app with Node.js.

I am currently using the validator package to validate inputs. I would like to have only alphanumeric characters allowed, but with the period, underscore and hyphen allowed also. (. _ -)

Some sample code is below:

if (!validator.isEmpty(username)) {
    console.log('Username not provided');
} else if (!validator.isAlphanumeric(username)) {
    console.log('Username is not alphanumeric');
} else {
    console.log('Good Username!');
}

I would like to have somewhere in the code above that checks for periods, underscores, and hyphens and allows them to get through the validator.isAlphanumeric method.

Thank you.

Answer 1

You need to use a regex for that.

if (!validator.matches(username, "^[a-zA-Z0-9_\.\-]*$")) {
  console.log('Username not valid');
} else {
  console.log('Good Username!');
}

Explanation:

^ : start of string
[ : beginning of character group
a-z : any lowercase letter
A-Z : any uppercase letter
0-9 : any digit
_ : underscore
\.: Escaped character. Matches a dot
\-: Escaped character. Matches a  minus
] : end of character group
* : zero or more of the given characters
$ : end of string

You can check the correctness here: https://regexr.com/4r65m