Rock, Paper, Scissors (Lizard, Spock, Enterprise, Klingon) for Node.js

README.md

Follow the docs in rps.js, or if you want to run with docker, save both rps.js and Dockerfile in the same directory, run:

$ docker build -t rps .
$ docker run -it --rm rps rock scissors
When rock faces scissors, rock wins!

DOCKERFILE

FROM node:latest
RUN mkdir /rps
COPY rps.js /rps/rps.js
ENTRYPOINT ["node", "/rps/rps.js"]

rps.js

const rpsThrows = process.argv.slice(2);
const matrix = {
  rock: {
	beats: ['scissors','lizard', 'enterprise']
  },
  paper: {
	beats: ['rock', 'spock', 'klingon']
  },
  scissors: {
	beats: ['paper', 'lizard', 'scissors']
  },
  lizard: {
    beats: ['paper', 'spock', 'scissors']
  },
  spock: {
    beats: ['rock','klingon', 'enterprise']
  },
  enterprise: {
	beats: ['paper', 'scissors', 'lizard']
  },
  klingon: {
	beats: ['lizard', 'scissors', 'rock']
  }
}

processRpsThrows();

/* Private functions for processing RPS Matches */

function processRpsThrows(matrix, rpsThrows){
  // make sure all throws are valid
  validateRpsMatch()

  // determine winner
  var rpsMatchWinner = determineRpsMatchWinner();

  // display results
  displayRpsMatchResults(rpsMatchWinner);
}


// ensures RPS Matchthrows are valid
function validateRpsMatch(){
  rpsThrows.forEach(arg => ensureRpsThrowIsValid(arg))

  if (rpsThrows.length != 2){
	exitRpsMatchWithError('ERROR: Exactly 2 throws must be provided')
  }

  if (rpsThrows[0] === rpsThrows[1]){
	exitRpsMatchWithError('NO WINNER, both throws are the same')
  }
}

// ensure a given thrown is valid
function ensureRpsThrowIsValid(arg){
  if (matrix[arg] === undefined) {
  	exitRpsMatchWithError(`ERROR: ${arg} is not a valid throw`);
  }
}

// determine the winner of the match
function determineRpsMatchWinner(){
  //if (matrix[rpsThrows[0]]['beats'] == rpsThrows[1])
  if (matrix[rpsThrows[0]]['beats'].indexOf(rpsThrows[1]) > -1 ){
    return rpsThrows[0]	
  } else {
    return rpsThrows[1]
  }
}

function displayRpsMatchResults(winner){
  console.log(`When ${rpsThrows[0]} faces ${rpsThrows[1]}, ${winner} wins!`)
}

function exitRpsMatchWithError(message){
  console.error(message)
  process.exit(1)
}