My factorial program does not work (in javascript)

Question

function factorial(num) {
  var factorialValue = 1;
  if (num === 0) {
    return factorialValue;
  } else {
    for (var i = num; i <= 1; i--) {
      factorialValue *= i;
    }
    return factorialValue;
  }
}

console.log(factorial(10));
console.log(factorial(5));
console.log(factorial(3));
console.log(factorial(0));

What's the problem in my code? It works only 1.

// thx for your codes!!!

Does this answer your question? [What is the fastest factorial function in JavaScript?](https://stackoverflow.com/questions/3959211/what-is-the-fastest-factorial-function-in-javascript) — vrintle, Apr 09 '20 at 12:22

score 1 · Answer 1 · edited Apr 09 '20 at 12:38

1

function factorial(num) {
  var factorialValue = 1;
  for (var i = num; i > 1; i--) {
    factorialValue *= i;
  }
  return factorialValue;
}

console.log(factorial(10));
console.log(factorial(5));
console.log(factorial(3));
console.log(factorial(0));

But I think you can use memoization (or recursion) instead of for-loops.

function factorial (n){
  if (n==0 || n==1)
    return 1;
  return factorial(n-1)*n;
} 

console.log(factorial(10));

edited Apr 09 '20 at 12:38

vrintle

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answered Apr 09 '20 at 12:12

Kid

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You can also remove the __if__ condition, as `0<1` evaluates to false before the very first iter. However, it'll make it ~1% cryptic. – vrintle Apr 09 '20 at 12:17

score 0 · Answer 2 · answered Apr 09 '20 at 12:41

You can use a more simple code, using recursion. Enjoy!

function factorial(num) {
  if (num === 0) {
    return 1;
  } else {
    return num * factorial(num-1);
  }
}

console.log(factorial(10));
console.log(factorial(5));
console.log(factorial(3));
console.log(factorial(0));

My factorial program does not work (in javascript)

2 Answers2