Factorial

function factorialOf(inputNum) {
  let num = parseInt(inputNum);
  let result = 1;
  for (let i = 2; i <= num; i++) {
    result *= i;
  }
  return result;
}

let inputNum = prompt("enter a number to calculate its factorial");

let factorial = factorialOf(inputNum);

console.log(factorial);

Palindrome Checker

function palindromeChecker(word) {
  let wordArr = word.split("");

  let revWord = [];
  for (let i = wordArr.length - 1; i >= 0; i--) {
    revWord.push(wordArr[i]);
  }

  let newWord = wordArr.toString();
  let newRevWord = revWord.toString();

  if (newWord === newRevWord) {
    return true;
  } else {
    return false;
  }
}

let word = prompt("Enter a word to check if it is a palindrome or not: ");

let answer = palindromeChecker(word);

console.log(answer);

Prime Checker

function isPrime(inputNum) {
  let num = parseInt(inputNum);

  if (num === 1 || num === 2) {
    return "is prime";
  } else {
    let i = 2;
    while (i < num) {
      if (num % i === 0) {
        return "not prime";
      }
      i++;
    }
    return "is prime";
  }
}

let inputNum = prompt("input a number to check if it is prime: ");

let answer = isPrime(inputNum);
console.log(answer);