ES Monsters

es-monsters.js

// A private name used by the Monster class
const pHealth = Name.create();
 
class Monster {
  
  // A method named "new" defines the class’s constructor function.
  new(name, health) {
  
    this.name = name;
    this[pHealth] = health;
  }
 
  // An identifier followed by an argument list and body defines a
  // method. A “method” here is simply a function property on some
  // object.
  attack(target) {
  
    log('The monster attacks ' + target);
  }
 
  // The contextual keyword "get" followed by an identifier and
  // a curly body defines a getter in the same way that "get"
  // defines one in an object literal.
  get isAlive() {
  
    return this[pHealth] > 0;
  }
 
  // Likewise, "set" can be used to define setters.
  set health(value) {
  
    if (value < 0) {
      throw new Error('Health must be non-negative.')
    }
    
    this[pHealth] = value
  }
  
  // We can create arbitrary properties on the prototype by
  // using the prototype keyword
  prototype {
  
    numAttacks: 0,
    attackMessage: 'The monster hits you!'
  	
  }
  
  // Class properties can be added using a static property initializer
  static {
  
    allMonsters: []
    
  }
  
  // Class methods can be added using the static method modifier
  static numMonsters() {
  
    return this.allMonsters.length;

  }
  
}