Iterative Factorial in JavaScript

"use strict";
// Iterative Factorial in JavaScript
//
// PURPOSE
// Factorial counts permutations of n distinct objects. Iterative multiplication avoids
// recursion and its call-stack overhead.
//
// METHOD
// Start with the empty product one. Multiply successively by every integer from two through
// n. After each multiplication the accumulator is the factorial of the current index.
//
// COMPLEXITY
// O(n) multiplications and O(1) auxiliary space; arbitrary-precision arithmetic costs are
// excluded.
//
// CONTRACT
// n >= 0. For a portable signed 32-bit result use n <= 12. Factorial grows quickly.
// Public APIs infer array lengths except in C, which accepts pointer/length pairs. Vertex
// counts and matrix dimensions remain explicit. Arrays must contain signed 32-bit integers.
// Sorted order, correct tree topology, and caller-owned data-structure invariants are
// preconditions; checking them on every query would change query complexity.
// Scalar and shape checks are included. Value-range checks are included where needed to
// prevent invalid indexing or nontermination. Allocation sizes are capped at 4,000,000
// workspace entries. Arithmetic outside Python raises an error on 32-bit overflow; Python
// uses arbitrary precision. Native allocation failures propagate. In-place outputs may be
// partly updated after arithmetic failure. These are single-threaded, in-memory
// implementations.
//
// LANGUAGE DETAILS
// Node.js 18+: Int32Array inputs and workspaces provide compact integer storage. Automatic
// lengths and checked arithmetic reject values outside signed 32-bit. Invalid inputs or
// overflow throw RangeError.
//
// EXAMPLE
// Expected return: 1.
// Run: node example.js
// Tests for this exact source artifact run before publication. The accompanying source
// archive includes unit cases, runtime results, and source hashes.

function alg_require(valid) { if (!valid) throw new RangeError("invalid algorithm input"); }
function alg_checked(v) { if (!Number.isInteger(v) || v < -2147483648 || v > 2147483647) throw new RangeError("32-bit result overflow"); return v; }
function alg_add(a,b) { return alg_checked(a+b); }
function alg_sub(a,b) { return alg_checked(a-b); }
function alg_mul(a,b) { return alg_checked(a*b); }
function alg_size(n) { alg_require(Number.isInteger(n) && n>=0 && n<=4000000); return n; }

function factorial(n) {
    alg_require(Number.isInteger(n) && n >= -2147483648 && n <= 2147483647);
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require(((n >= 0) && (n <= 12)));
    let result = 1;
    let i = 2;
    while ((i <= n)) {
        result = alg_mul(result, i);
        i = alg_add(i, 1);
    }
    return result;
}

let n = 0;
let result = factorial(n);
console.log(result);