For factorials of sufficient size, Javascript is unable to process them. I have written this to allow for larger factorials by using an array of single digits to base the math on.
Using factorial.js
For finding the factorial of a number, call:
> factorial(10)
"3628800"
> factorial(50)
"30414093201713378043612608166064768844377641568960512000000000000"If you wish to see the array form of the number, call:
> factorial(10, true)
[3, 6, 2, 8, 8, 0, 0]
> factorial(50, true)
[3, 0, 4, 1, 4, 0, 9, 3, 2, 0, 1, 7, 1, 3, 3, 7, 8, 0, 4, 3, 6, 1, 2, 6, 0, 8, 1, 6, 6, 0,
6, 4, 7, 6, 8, 8, 4, 4, 3, 7, 7, 6, 4, 1, 5, 6, 8, 9, 6, 0, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0]Given ECMA Section 8.5 - Numbers, 9007199254740992 is the maximum integer Javascript allows.
As a result of this limit, this code should theoretically work up to 1000799917193443!.
Given that each iteration multiplies the array components by the next highest integer up to the desired factorial and that the highest possible multiple in the array is a single digit: 9, at the final iteration you would possibly be multiplying 1000799917193443 * 9 = 9007199254740987 at each index in the array.