(More) Advanced JavaScript

Question 1

Why do we need a single source of truth? (from data modeling)

Answer 1

• Place to store our data for when we need to manipulate it

- Easier to access and update

Question 2

What is a method?

Answer 2

Function on an object

Question 3

What does a method do?

Answer 3

Whatever you tell it to do like functions

Question 4

What is this?

Answer 4

refers to the object that the function was declared in (either an object itself or the window)

Question 5

What does bind do?

Answer 5

bind is a method that changes ‘this’ to whatever object is specified in the argument

Question 6

What is the difference between a function and an object literal?

Answer 6

**functions are CALLABLE objects! have three methods - apply, call, bind!

Question 7

What is Prototypal Inheritance?

Answer 7

The inheritance of certain methods and properties from the Prototype property of other objects

Question 8

What is the Prototypal Chain?

Answer 8

The way in which javascript looks for methods or properties in an object; if doesnt find it in this object, will go up to the next prototype in the chain

Question 9

In the custom objects we created, I noticed that our prototype object has another __proto__ property, where did that come from?

Answer 9

Created a new object with {} and inherited from Object

Question 10

Why does JavaScript have Prototypal Inheritance?

Answer 10

Efficiency and memory (how much memory RAM your program takes up)
use as little memory as possible

Question 11

What does the new keyword do?

Answer 11

• creates a blank JS object
• sets the constructor of this new object to another object
• the new object becomes the “this”
• returns this new object

Question 12

I could’ve added a method to the constructor function by assigning a method to a property on the this object. Why do we have to add it to the prototype property?

Answer 12

** save memory and space

Question 13

What is the first thing that happens in a class when it is instantiated with the new keyword?

Answer 13

The constructor runs to create a new object using the specified arguments

Question 14

Since classes are technically functions as well. Can you name a difference between classes and functions?

Answer 14

Class are not hoisted like functions are

Question 15

What is a static method?

Answer 15

Static methods are called without instantiating their class and cannot be called through a class instance.

• *Static methods are utility functions
• *can use without creating an instance, attached to creator Array, Object
  ex. Array.isArray(arr) // true

Question 16

What is the benefit of instantiating Classes within other classes?

Answer 16

• • Has a tie from the parent to child, parent always has reference to the child
• • pass in info from parent to child

Question 17

Why are parent - child relationships important in OOP?

Answer 17

Modeling the real world using data, show how groups of information are related to and relent on each other
**OOP confined to their bubble –> create a tether from one bubble to another

Question 18

What is the basic idea of OOP?

Answer 18

MDN - The basic idea of OOP is that we use objects to model real world things that we want to represent inside our programs, and/or provide a simple way to access functionality that would otherwise be hard or impossible to make use of.
LFZ - creating a separate space and organization for keeping everything together and pairing data and functionality

Question 19

Why did you have to bind this for the feedChild method in the Parent class?

Answer 19

Otherwise the this will be the Child class

Question 20

Why is it important to assign callback methods to properties in the constructor?

Answer 20

So they will be added to the each object instance upon creation and can be used in each object

Question 21

Why did the Maker class require all of the Parent class info?

Answer 21

The maker class instantiating the parent class

Question 22

Why did you have to bind this for the replenishFood method.

Answer 22

Otherwise the this will be the parent class

Question 23

What decides the order in which JS files must be loaded?

Answer 23

HTML document, what is getting instantianted by what and what data is needed by what objects

Question 24

Instantiation (definition)

Answer 24

The process of taking a class definition and creating an object (or instance) from it

Question 25

Instance (definition)

Answer 25

the object that is created from the instantiation process

Question 26

What are classes?

Answer 26

Syntactical sugar for prototypical inheritance modeled after object oriented programming languages; special functions

Question 27

Polymorphism (definition)

Answer 27

The ability of multiple object types to implement the same functionality
MDN - In the case of OOP, by making the class responsible for its code as well as its own data, polymorphism can be achieved in that each class has its own function that (once called) behaves properly for any object.

Question 28

Constructor functions

Answer 28

Used to define and initialize objects and their features

MDN - The Function constructor creates a new Function object. Calling the constructor directly can create functions dynamically, but suffers from security and similar (but far less significant) performance issues to eval. However, unlike eval, the Function constructor creates functions which execute in the global scope only.