README.md

primality.js

Primality is a JavaScript library for prime numbers. It features a fantastic primality test and identification of the various classes of prime numbers.

Features

• Check the primality of a number
• Works with numbers disguised as strings
• Also does arrays
• Provides checks for the following classes of prime numbers:
  • twin
  • cousin
  • sexy
  • Wilson
• About 1 kibibyte minified and gzipped
• ESM support

Installation

$ npm install primality

Usage

Primality's flagship method is primality(), which works as you might expect it to:

import primality from 'primality';

primality(7);
// => true

primality(6);
// => false

Of course, you can pass strings instead of numbers if you'd like:

primality('13');
// => true

Primality can even do arrays. If any of the values in an array are not prime, false is returned.

primality([17, 19, 23]);
// => true

primality([17, 20, 23]);
// => false

Beyond primality testing, Primality can also tell you if a pair of numbers are twin, cousin, or sexy primes. Twin primes are prime numbers that differ from each other by two. Similarly, cousin primes differ by four and sexy primes differ by six.

import { areCousinPrimes, areSexyPrimes, areTwinPrimes } from 'primality';

areCousinPrimes(3, 7);
// => true

areSexyPrimes(5, 11);
// => true

areTwinPrimes(3, 5);
// => true

You can also check for Wilson primes. Only three Wilson primes are known at the moment: 5, 13, and 563.

import { isWilsonPrime } from 'primality';

isWilsonPrime(563);
// => true