Javascript prototypes

prototype_inheritance.js

/** 
 * Class definition for Monster
 */
function Monster(name) {
    this.health = 1000;
    this.attack = 100;
    this.name = name;
}

Monster.prototype.attack = function(other) {
    other.health -= this.attack;
}

Monster.prototype.special_attack = function(other) {
    if (other.health <= 0) {
        other.health = 0;
        console.log(this.name + ' died');
    }
}
/* End class definition */

/** 
 * Class definition for Wizard
 */
function Wizard(name) {
    // call the parent constructor
    Monster.call(this, name);

    this.magic = 300;
    this.spell_attack = 150;
}
Wizard.prototype = Object.create(Monster.prototype);

// overrides the parent function
Wizard.prototype.special_attack = function(other) {
    if (this.magic >= this.spell_attack)  {
        other.health -= this.spell_attack;
        this.magic -= this.spell_attack;

        console.log('Cast spell');
    } else { 
        console.log('Not enough magic to cast a spell');
    }

    // call the parent function
    Object.getPrototypeOf(Human.prototype).special_attack.call(this, other);
}
/* End class definition */

/** 
 * Class definition for Human
 */
function Human(name) {
    // call the parent constructor
    Monster.call(this, name);

    this.arrow_count = 3;
    this.arrow_attack = 125;
}
Human.prototype = Object.create(Monster.prototype);

// overrides the parent function
Human.prototype.special_attack = function(other) {
    if (this.arrow_count > 0)  {
        other.health -= this.arrow_attack;
        this.arrow_count--;
        console.log('Shot arrow')
    } else {
        console.log('No more arrows')
    }

    // call the parent function
    Object.getPrototypeOf(Human.prototype).special_attack.call(this, other);
}
/* End class definition */

var wizard = new Wizard('Merlin');
var human = new Human('John Cena');

wizard.special_attack(human);

for (var i = 0; i < 12; i++) {
    human.special_attack(wizard);
    human.arrow_count++;
}

prototypes.js

// this is the constructor of the Person object
function Person(name, age, email) {
    // instance variables
    this.name = name || "";
    this.age = age || 0; 
    this.email = email || "";
}

// a class method (aka functions as static variables)
Person.prototype.print = function() {
    console.log(this.name += " is " + this.age.toString() + " years old.");
};

Person.prototype.canBuyAlcohol = function() {
    return this.age >= this.DRINKING_AGE;
}

// static variable
Person.prototype.DRINKING_AGE = 21;

var adam = new Person('Adam', 22, '[email protected]');
var billy = new Person('Billy', 19, '[email protected]');

// overriding the drinking age for only billy, the interpreter first checks the instance variables and then
// checks the variables in the prototype so it will go with this instance value
billy.DRINKING_AGE = 19;