Infinite Rock Paper Scissors

rps.js

function rps(game, a, b) {
	if (a == b) return 0 // Tie
	const r = game.indexOf(a) - game.indexOf(b)
  // An even number will decide "A" winner for positive numbers, odd for negative
	return r % 2 == (r < 0 ? 0 : 1)
}

// Game elements lenght must be an odd number
const games = [
	[ // Original
		'rock',
		'paper',
		'scissors'
	],
	[ // http://samkass.com/theories/RPSSL.html
		'rock',
		'paper',
		'scissors',
		'spock',
		'lizard'
	],
	[ // https://www.facebook.com/RockPaperScissorLizardSpockCrocSnake/	
		'rock',
		'paper',
		'scissors',
		'spock',
		'lizard',
		'croc',
		'snake'
	],
	[ // https://www.mithrandir.com/RockPaperScissors/RockPaperScissors.shtml
		'rock',
		'paper',
		'scissors',
		'spock',
		'match',
		'phoenix',
		'lizard'
	],
	[ // https://www.johndcook.com/blog/2018/08/07/rock-paper-scissors-lizard-spock/
		'rock',
		'paper',
		'scissors',
		'spock',
		'hawking',
		'velociraptor',
		'lizard'
	],
	[ // Spiderman Batman + Wizard Glock
		'rock',
		'paper',
		'scissors',
		'spock',
		'spiderman',
		'batman',
		'wizard',
		'glock',
		'lizard'
	]
]

// This is a test, not the actual code.
// The keys of this object also works as game.
const elements = {
	rock: ['scissors', 'spiderman', 'wizard', 'match', 'hawking', 'lizard', 'snake'],
	paper: ['rock', 'spock', 'batman', 'glock', 'phoenix', 'velociraptor', 'croc'],
	scissors: ['paper', 'spiderman', 'wizard', 'match', 'hawking', 'lizard', 'snake'],
	spock: ['rock', 'scissors', 'batman', 'glock', 'phoenix', 'velociraptor', 'croc'],
	spiderman: ['paper', 'spock', 'wizard', 'match', 'hawking', 'lizard', 'snake'],
	batman: ['rock', 'scissors', 'spiderman', 'glock', 'phoenix', 'velociraptor', 'croc'],
	wizard: ['paper', 'spock', 'batman', 'match', 'hawking', 'lizard', 'snake'],
	glock: ['rock', 'scissors', 'spiderman', 'wizard', 'phoenix', 'velociraptor', 'croc'],
	match: ['paper', 'spock', 'batman', 'glock', 'hawking', 'lizard', 'snake'],
	phoenix: ['rock', 'scissors', 'spiderman', 'wizard', 'match', 'velociraptor', 'croc'],
	hawking: ['paper', 'spock', 'batman', 'glock', 'phoenix', 'lizard', 'snake'],
	velociraptor: ['rock', 'scissors', 'spiderman', 'wizard', 'match', 'hawking', 'croc'],
	lizard: ['paper', 'spock', 'batman', 'glock', 'phoenix', 'velociraptor', 'snake'],
	croc: ['rock', 'scissors', 'spiderman', 'wizard', 'match', 'hawking', 'lizard'],
	snake: ['paper', 'spock', 'batman', 'glock', 'phoenix', 'velociraptor', 'croc']
}

function test() {
	// Test for the test
	const keys = Object.keys(elements)
	if (keys.length % 2 == 0)
		return `❌ Elements length must be odd`
	const length = ~~(keys.length / 2), count = {}
	for (const element in elements)
		if (elements[element].length != length)
			return `❌ ${element} must beat ${length} element${length == 1 ? '' : 's'}`
		else if (elements[element].includes(element))
			return `❌ ${element} can't beat itself`
		else
			for (const key of elements[element])
				if (!elements.hasOwnProperty(key))
					return `❌ ${key} is not a valid element`
				else if (elements[key].includes(element))
					return `❌ ${element} and ${key} can't beat eachother`
				else if (count.hasOwnProperty(key))
					count[key] += 1
				else
					count[key] = 1
	for (const key in count)
		if (count[key] != length)
			return `❌ ${key} must be defeated ${length} time${length == 1 ? '' : 's'}`

	for (const a of keys)
	for (const b of keys)
		if (rps(keys, a, b) != elements[a].includes(b))
			return `❌ ${a} must ${elements[a].includes(b) ? 'win' : 'lose'} against ${b}`

	// The actual test
	for (const game of games)
		if (game.length % 2 == 0)
			return `❌ Game #${games.indexOf(game)} length must be odd`
		else
			for (const a of game)
			for (const b of game) 
				if (rps(game, a, b) != elements[a].includes(b))
					return `❌ Game #${games.indexOf(game)} > ${a} must ${elements[a].includes(b) ? 'win' : 'lose'} against ${b}`

	return `☑️ OK`
}

console.log(test())