Simple validation of a username with regex

Simple validation of a username with regexCodewars

Solution

JavaScript

const validateUsr = (username) => {
  return username.length >= 4
    && username.length <= 16
    && (username.match(/[a-z]|_|\d/g).length === username.length);
};

Best practice on codewars

JavaScript

function validateUsr(username) {
  /**
   - `^`        Start from the beginning of the string.
   - `[]`       Allow any character specified, including...
   - `a-z`      anything from a to z,
   - `0-9`      anything from 0 to 9,
   - `_`        and underscore.
   - `{4,16}`   Accept 4 to 16 of allowed characters, both numbers included.
   - `$`        End the string right after specified amount of allowed characters is given.
   */
  const validator = /^[a-z0-9_]{4,16}$/;
  
  return validator.test(username);
}