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

A module to determine whether the numeric is prime.

import { bigintRootApproximate } from "./_bigint_root_approximate.js";
/**
 * 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 ||
        itemBigInt === 3n ||
        itemBigInt === 5n ||
        itemBigInt === 7n) {
        return true;
    }
    if (itemBigInt < 2n ||
        itemBigInt % 2n === 0n ||
        itemBigInt % 3n === 0n ||
        itemBigInt % 5n === 0n ||
        itemBigInt % 7n === 0n) {
        return false;
    }
    const divisorMaximum = bigintRootApproximate(itemBigInt).ceil;
    for (let divisor = 3n; divisor <= divisorMaximum; divisor += 2n) {
        if (itemBigInt % divisor === 0n) {
            return false;
        }
    }
    return true;
}
export default isNumericPrime;