I don't understand why this is an instance of TodoListItem.

Think of a constructor function as a factory that creates objects. This factory produces ToDoListItems. When you call the constructor function with the 'new' keyword, it produces a unique ToDoListItem, and it is stored as task. This unique product is known as an instance.

'Task' is not a constructor function. It is not the factory, it's the product.

I thought that I might try to weigh in on this. I think that thing tripping everyone up is probably the "this" key word. To conceptualize the idea of a constructor function, I tried using static code so that it was more relateable.

// CONSTRUCTOR FUNCTION (TEMPLATE) FOR ZOO ANIMALS

function Animal(type, age, name, noise) {
  // sample output of the object that this constructor will build 
  /* this (instance #1 animal) = {
        type: "Cat",
        age: 5,
        name: "Cuddles",
        sound: "Meow",
        makeNoise: function() {alert("Meow");}
   } */

  /* this (instance #2 animal) = {
        type: "Elephant",
        age: 27,
        name: "Biggie",
        sound: "Trumpet",
        makeNoise: function() {alert("Trumpet");}
   } */

/* template based on constructor */
  this.type = type;
  this.age = age;
  this.name = name;
  this.noise = noise;
  this.makeNoise = function() {alert(this.noise)};
}

// FOUR INSTANCES of the Constructor Animal
var cat = new Animal("Cat", 5, "Cuddles", "Meow");
var elephant = new Animal("Elephant", 27, "Biggie", ");
var tiger = new Animal("Cat", 8, "Tony", "Roar", "Trumpet");
var zebra = new Animal("Zebra", 5, "Stripes", "Neigh");

Andrew Chalkley, as time permits, can you and the Treehouse crew consider a rework of the JavaScript constructor video? I think it would help to have a breakdown of the constructor concept without using "this", then introducing both the constructor and "this" concepts later on in the video after there's a solid foundation for the purpose behind a constructor and how it actually creates separate object instances using hard coded tangible properties and methods. The code above is meant to assist with some brainstorming around that idea. It's still pretty rough, but hopefully you get what I'm saying. Thanks!

im still SOOOO confused...

you said: 'Task' is not a constructor function. It is not the factory, it's the product.

witch means that var balrog = new Monster("Captain");

its not the factory either.

that puts me back where i started, both pieces of code are the same ( not sure what they are /: )

I break that code in two parts.

FIRST:

function TodoListItem(description) {
  this.description = description;
  this.isDone = false;
  this.toString = function() {
    return this.description;
  }
  this.markAsComplete = function() {
    this.isDone = true;
  }
}

TWO:

var task = new TodoListItem("Do the laundry!");

when i see both pieces of code the one with the monsters and the one with the TodoListItem they're pretty much similar i mean to me they're the same is essence... keep wondering whats the real difference...

Andrew Chalkley Your assistance would be more than appreciated in this matter.

Andrew Chalkley so in this case:

function Monster(rank) {
  this.rank = rank;
  this.health = 100;
  this.takeHit = function() {
    this.health--;
  }
  this.isDead = function() {
    return this.health <= 0;
  }
}

var monster = new Monster("Captain");

var monster its an instance of Monster(), right?

I think that all my confusion came from monster - Monster I think that you guys should change that example from the quiz ( or was it on purpose? ).

I had the concept pretty much clear before I got the quiz and I think that quiz got me confused.