cactus-josh

cactus-josh is a JavaScript implementation of the classic CactusKev poker hand evaluator, originally written in C by Kevin Suffecool. One of the cleverest bits of code ever written, this algorithm represents the 52 cards of a French deck with unsigned 32-bit d-words, each of which corresponds to a prime number. It then uses bitshifting and lookup tables to calculate the value of a hand of five cards. It's insanely fast!

Instructions for use

Install/require, then generate a new deck with fullDeck(). Convert each card to a string with cardName( card ):

const cactus = require( "cactus-josh" );

// pass any non-null argument to shuffle the deck
const shuffledDeck = cactus.fullDeck( true );

const drawFive = shuffledDeck.slice( 0, 5 );

console.log( drawFive.map( cactus.cardName ) );
--> [ 'Nine of Clubs', 'Ten of Clubs', 'Six of Clubs', 'Nine of Diamonds', 'Five of Diamonds' ]

There are 2,598,960 (52-combination-5) possible five-card hands. Each hand has a unique rank, from 7,462 (the lowest possible hand) to 1 (a royal flush of spades). Use handValue( hand ) to return a hand's number rank, and handRank( hand ) to return a string of the hand type:

console.log( cactus.handValue( drawFive ) ) );
--> 4601

console.log( cactus.handRank( drawFive ) ) );
--> One pair