5, 6, 7 or 8 char length of random numbers and/or letters

function getRandomIntinRange(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

let DEFAULT_END_OF_PROGRAM_MESSAGE = "end of program";
let DEFAULT_WRONG_COMMAND_MESSAGE = "the fuck are you typing";
let DEFAULT_STRING_MIN_SIZE = 5;
let DEFAULT_STRING_MAX_SIZE = 8;
let DEFAULT_LETTER_A_POSITION = 65;
let DEFAULT_LETTER_Z_POSITION = 90;
let lettersArray = [];
let numbersArray = [];

for (let i = DEFAULT_LETTER_A_POSITION; i <= DEFAULT_LETTER_Z_POSITION; i++) {
  lettersArray.push(String.fromCharCode(i));
}

for (let i = 0; i <= 9; i++) {
  numbersArray.push(i);
}

let answer = prompt('', 'next');

if (answer === "end") {
  console.log(DEFAULT_END_OF_PROGRAM_MESSAGE);
} else {
  let currentString = [];
  let currentStringSize;
  let currentCharType;

  while (answer === "next") {
    currentStringSize = getRandomIntinRange(DEFAULT_STRING_MIN_SIZE, DEFAULT_STRING_MAX_SIZE);

    for (let i = 0; i <= (currentStringSize - 1); i++) {
      currentCharType = Math.floor((Math.random() * 2));
      if (currentCharType === 0) {
        currentString.push(lettersArray[getRandomIntinRange(0, (lettersArray.length - 1))]);
      } else {
        currentString.push(numbersArray[getRandomIntinRange(0, (numbersArray.length - 1))]);
      }
    }

    console.log(currentString.join(""));
    currentString = [];

    answer = prompt('', 'next');

    if (answer === "end") {
      console.log(DEFAULT_END_OF_PROGRAM_MESSAGE);
      break;
    }
  }
}