JavaScript/Maths/Factorial.js at master · TheAlgorithms/JavaScript · GitHub

39 lines (32 loc) · 848 Bytes

author: PatOnTheBack

license: GPL-3.0 or later

Modified from:

https://github.com/TheAlgorithms/Python/blob/master/maths/factorial_python.py

This script will find the factorial of a number provided by the user.

More about factorials:

https://en.wikipedia.org/wiki/factorial

'use strict'

const calcRange = (num) => {

return [...Array(num).keys()].map((i) => i + 1)

}

const calcFactorial = (num) => {

if (num === 0) {

return 1

}

if (num < 0) {

throw Error('Sorry, factorial does not exist for negative numbers.')

}

if (!num) {

throw Error(

'Sorry, factorial does not exist for null or undefined numbers.'

)

}

if (num > 0) {

const range = calcRange(num)

const factorial = range.reduce((a, c) => a * c, 1)

return factorial

}

export { calcFactorial }

Expand file tree