character.js

// Declare a variable that will later store the selected character and enemy
var selectedCharacter;
var selectedEnemy;

// Define a constructor
window.Character = function(params) {
  _.extend(this, params);
};

// Give all characters an attack function
Character.prototype.attack = function(enemy) {
  enemy.health = enemy.health - this.attack;
  $(document).trigger('health:changed');
};

// Create some character instances
window.characters = {
  'Bulbasaur': new Character({
    health: 12,
    attack: 1
  }),

  'Charizard': new Character({
    health: 6,
    attack: 2
  })
};

$(document).on('character:selected', function(character) {
  selectedCharacter = character;
});

$(document).on('enemy:selected', function(enemy) {
  selectedEnemy = enemy;
});

$(document).on('attack:enemy', function() {
  selectedCharacter.attack(selectedEnemy);
});