I'm not sure why it gives this result (4320)

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I'm not sure why it gives this result (4320)

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#1 by (2 votes)

2

I do not understand why this result gives me, someone would explain to me a little the why of this result please?

function a(n){
  if (n === 0) {
    return 1;
  } else {
    return a(n - 1) * n;
  }
}

console.log(a(8)); // => 4320

javascript if

asked by fran 09.12.2017 в 02:40

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1 answer

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score 2 · Answer 1

Your function is known as recursion in Javascript. And it serves to calculate the factorial of a given number.

In the case of the example, the factorial of 8 would be 40320 .

If you pass the number 9 for example, it would result in 362880 .

The recursion in Javascript is explained for example in:

Recursivity (JavaScript)

And what happens in your code is explained in more detail in this SO question in English:

Fast factorial function in JavaScript

This function is more perfect, because it handles, for example, negative numbers and zero:

function factorial(num)
{
    // Si el número es menor que 0, lo rechaza
    if (num < 0) {
        return -1;
    }
    // Si el número es 0, su factorial es 1
    else if (num == 0) {
        return 1;
    }
    // En caso contrario, llama la función recursiva otra vez
    else {
        return (num * factorial(num - 1));
    }
}

var result = factorial(8);
console.log(result);
var result = factorial(-8);
console.log(result);
var result = factorial(0);
console.log(result);
var result = factorial(9);
console.log(result);