check if the char is alphanumeric

char.js

// source: https://stackoverflow.com/questions/4434076/best-way-to-alphanumeric-check-in-javascript 
// i just edited a little bit
/**
 *
 * @param {string} char
 * @returns
 */
function isAlphaNumeric(char) {
  let code = char.charCodeAt(0);
  if (
    !(code > 47 && code < 58) && // numeric (0—9)
    !(code > 64 && code < 91) && // upper alpha (A—Z)
    !(code > 96 && code < 123) // lower alphaa (a-a)
  ) {
    return false;
  }
  return true;
}