compare-faster.js

var _dictionary = {
  'rock,scissors': 'Rock',
  'rock,paper': 'Paper',
  'scissors,paper': 'Scissors'
};

function compare(a, b) {
  var result;
  if (a === b) {
    result = 'Result is a tie';
  } else {
    result = _dictionary[[a,b].join(',')] || _dictionary[[b,a].join(',')];
  }
  return [result, 'wins!'].join(' ');
}

compare('scissors', 'rock');