factorial of a number

Question

I have the following code but it is not giving perfect result for factorial can u find it out plz

Answer 1

Here is one I made using a while loop:

function factorialize(num) 
{
  i = 1;
  b = 1;
  while (i < num) {
    b = b + (b * i);
    i = i + 1;
    }
return b;
}

Answer 2

I am not sure why no one used dynamic programming to answer this, it's by far the most efficient way to build something on a factorial in my view.

 var mem = [];

 function fact(num)
 {
    var x = parseInt(num);

    if (x == 0 || x == 1) return 1;

    mem[x] = x * fact(x-1);

    return mem[x];
 }

Answer 3

My suggestion:

function fact(x) {
    if (x<0) {
        return Infinity
    };
    var _= 1
    for ($=1;$<=x;++$) {
        _*=$
    };
    return _
};

It simply returns the factorial of whatever "x" is.

Answer 4

A slight edit to Anton's code:

function fact(x) {
   if(x>0)
       return x* fact(x-1);
   if(x===0)
       return 1;
   return null;

}

(factorial of a negative doesn't exist, but factorial of 0 is equal to 1, in this case, if a number is smaller than 0, the function will return null)

Answer 5

a very simple form:

function fact() {
    var x = document.getElementById("txtf").value;
    var f=1;
    for (var i=1; i <= x ; i++){
        f = f*i;
    }
    document.getElementById('showR').innerHTML= f;
}


 <input type="text" id="txtf" value="3">
   <input type="button" id="btnf" value="click for calculate" onclick="fact()">
   <p id="showR">/Factoriel/</p>

Answer 6

1. Your function doesn't return anything, ever.
2. What do you do when x is 0?
3. Minor point - apart from alert, you don't really do anything with the returned value.

Try this instead, if you will (hover over the text):

if(x==0) return 1;
return x * fact(x-1);

Working example: http://jsbin.com/apuka3/2