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Calculate Factorial

factorial​

The factorial function computes the factorial of a non-negative numeric value recursively.

Function Signature​

factorial(int: Numeric | undefined): number | undefined

Parameters​

  • int: A numeric input value or numeric string whose factorial should be calculated. Can also be undefined.

Return Value​

  • Returns the factorial result as a number if the input is valid.
  • Returns undefined if the input is negative, not numeric, non-integer or undefined.

Example Usage​

import { factorial } from 'nhb-toolbox';

factorial(5);           // 120
factorial(0);           // 1
factorial(1);           // 1
factorial(-3);          // undefined
factorial(undefined);   // undefined
factorial(5.5);         // undefined

Aliases​

factorial can also be imported using the following aliases:

  • getFactorial: Alias for factorial.
  • calculateFactorial: Alias for factorial.

Notes​

  • The function uses a recursive approach internally.
  • Input is normalized via normalizeNumber before computation.
  • Factorial of 0 and 1 is 1.
  • It does not compute factorial for fractions (non-integer values).
  • Can return very large values quickly due to the rapid growth rate of factorial values.
  • Only non-negative integer values are considered valid for calculating factorial.

Conclusion​

The factorial function is useful for mathematical calculations involving permutations, combinations, and other scenarios where factorial values are required. It provides safe handling of invalid inputs by returning undefined for negative numbers, non-numeric and non-integer values, or undefined inputs.

See Also​