@hugoalh/is-numeric-prime/mod.js

A module to determine whether the numeric is prime.

import { bigintRootApproximate } from "./_bigint_root_approximate.js";
const primesKnown = [2n, 3n, 5n, 7n, 11n, 13n, 17n, 19n, 23n, 29n, 31n, 37n, 41n, 43n, 47n, 53n, 59n, 61n, 67n, 71n, 73n, 79n, 83n, 89n, 97n];
const primesPush = [];
/**
 * Determine whether the numeric is prime.
 * @param {bigint | number} item Item that need to determine.
 * @returns {boolean} Determine result.
 * @example 1
 * ```ts
 * isNumericPrime(9876);
 * //=> false
 * ```
 * @example 2
 * ```ts
 * isNumericPrime(8n);
 * //=> false
 * ```
 * @example 3
 * ```ts
 * isNumericPrime(17);
 * //=> true
 * ```
 * @example 4
 * ```ts
 * isNumericPrime(23n);
 * //=> true
 * ```
 */
export function isNumericPrime(item) {
    let itemBigInt;
    if (typeof item === "bigint") {
        itemBigInt = item;
    }
    else {
        if (!Number.isInteger(item)) {
            return false;
        }
        itemBigInt = BigInt(item);
    }
    if (itemBigInt < 2n) {
        return false;
    }
    const primes = [...primesKnown, ...primesPush];
    if (primes.includes(itemBigInt)) {
        return true;
    }
    if (primes.some((prime) => {
        return (itemBigInt > prime && itemBigInt % prime === 0n);
    })) {
        return false;
    }
    const rootCeil = bigintRootApproximate(itemBigInt).ceil;
    for (let divisor = primesKnown[primesKnown.length - 1] + 2n; divisor <= rootCeil; divisor += 2n) {
        if (itemBigInt % divisor === 0n) {
            return false;
        }
    }
    primesPush.push(itemBigInt);
    return true;
}
export default isNumericPrime;