es-next-tools/dist/math/perm.js

A comprehensive utility library for JavaScript and TypeScript that provides a wide range of functions for common programming tasks, including mathematical operations, date manipulations, array and object handling, string utilities, and more.

import { factorial } from "./factorial";
/**
 * Calculates the number of permutations (nPk).
 * @param {number} n - The total number of items.
 * @param {number} [k] - The number of items to arrange.
 * @returns The number of possible permutations.
 * @example
 * perm(3, 2); // 6
*/
export function perm(n, k) {
    if (k === undefined || k > n)
        return 0;
    return factorial(n) / factorial(n - k);
}