Object-Oriented Programming

Question 1

What is a method?

Answer 1

a function which is a property of an object.

Question 2

How can you tell the difference between a method definition and a method call?

Answer 2

method definition has function code block while method call has the method(arguments)

Question 3

Describe method definition syntax (structure).

Answer 3

property name : function method

Question 4

Describe method call syntax (structure).

Answer 4

object.method(arguments)

Question 5

How is a method different from any other function?

Answer 5

look for a dot too see if its a method if not its a function

Question 6

What is the defining characteristic of Object-Oriented Programming?

Answer 6

objects can contain both data (as properties) and behavior (as methods)

Question 7

What are the four “principles” of Object-Oriented Programming?

Answer 7

Abstraction, Encapsulation, Inheritance, and Polymorphism

Question 8

What is “abstraction”?

Answer 8

being able to work with (possibly) complex things in simple ways

Question 9

What does API stand for?

Answer 9

Application Programming Interface (API)

Question 10

What is the purpose of an API?

Answer 10

a way to interact with a system in a simplified, consistent fashion

Question 11

What is this in JavaScript?

Answer 11

it is a keyword that references the object

Question 12

What does it mean to say that this is an “implicit parameter”?

Question 13

When is the value of this determined in a function; call time or definition time?

Answer 13

call time because it is a parameter and a parameter is only called

Question 14

What kind of inheritance does the JavaScript programming language use?

Answer 14

prototype-based or prototypal

Question 15

What is a prototype in JavaScript?

Answer 15

a source for other objects to inherit its data and behavior within

Question 16

How is it possible to call methods on strings, arrays, and numbers even though those methods don’t actually exist on strings, arrays, and numbers?

Answer 16

its within the prototype object

Question 17

If an object does not have it’s own property or method by a given key, where does JavaScript look for it?

Answer 17

prototype

Question 18

What does the new operator do?

Answer 18

1. creates new object
2. assign _ _ proto _ _ under the prototype property
3. binds as the this context
4. if function doesn’t return anything

Question 19

What property of JavaScript functions can store shared behavior for instance created with new?

Answer 19

.prototype

Question 20

What does the instanceof operator do?