using else if statements to check for uppercase, lowercase, or number character [closed]

I've been trying to solve this question to check if a character is in uppercase, lowercase or is a number and I've been able to do it for the uppercase and lowercase but I can't do it for the number.

let letterOrNumber = prompt("Enter an uppercase letter, a lowercase letter or a number");

let upperCaseLetter = letterOrNumber.toUpperCase();
let lowerCaseLetter = letterOrNumber.toLowerCase();
let userNumber = parseInt(letterOrNumber)

if (letterOrNumber === upperCaseLetter) {
    console.log(letterOrNumber + " is an uppercase letter.");
}

else if (letterOrNumber === lowerCaseLetter) {
    console.log(letterOrNumber + " is a lowercase letter.");
}

else if (letterOrNumber === userNumber) {
    console.log(letterOrNumber + " is a number.");
}

else {
    console.log(letterOrNumber + " is not a letter or number");
}