Week 5 Quiz Questions

Question 1

What is a method?

Answer 1

A method is 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 call required an object to be associated with it. method definition is within an object, function keyword, etc.

Question 3

Describe method definition syntax (structure).

Answer 3

var object = {methodName: function (param) {code block}};

Question 4

Describe method call syntax (structure).

Answer 4

object.methodName(argument)

Question 5

How is a method different from any other function?

Answer 5

methods are directly related to the object they are associated with

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
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

Question 10

What is the purpose of an API?

Answer 10

a way for two or more computer programs to communicate with each other.

Question 11

What is this in JavaScript?

Answer 11

this is referring to calling object

Question 12

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

Answer 12

it is available in the function code block even though it wasnt included in the function definition or declared with var

Question 13

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

Answer 13

on function call

Question 14

What does this refer to in the following code snippet?
var character = {
firstName: ‘Mario’,
greet: function () {
var message = ‘It's-a-me, ‘ + this.firstName + ‘!’;
console.log(message);
}
};

Answer 14

this refers to the character object– character.firstName

Question 15

Given the above character object, what is the result of the following code snippet? Why?
character.greet();

Answer 15

‘It’s-a-me, Mario!”
‘this’ in .greet is directly referring to ‘character’

Question 16

Given the above character object, what is the result of the following code snippet? Why?
var hello = character.greet;
hello();

Answer 16

its a me undefined
‘this’ is now referring to the window object

Question 17

How can you tell what the value of this is for a particular function or method call?

Answer 17

look at the object left of the dot when the function is called

Question 18

What kind of inheritance does the JavaScript programming language use?

Answer 18

prototype-based/ prototypal inheritance

Question 19

What is a prototype in JavaScript?

Answer 19

prototypes allow objects to inherit behaviors (methods) and data (properties) from objects
[[Prototype]]

Question 20

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 20

using the Object.setPrototypeOf(object, prototype) method gives the selected object the functions/ methods of the prototype being entered.
via prototypal inheritance

Question 21

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

Answer 21

JS looks at its nearest prototype.

Question 22

What does the new operator do?

Answer 22

The new operator creates a new instance (instantiation) of an object that uses a constructor function as a blueprint

Question 23

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

Answer 23

prototypal inheritance

Question 24

What does the instanceof operator do?

Answer 24

tests to see if an object appears anywhere in a constructor. returns boolean

Question 25

What is a “callback” function?

Answer 25

a function that is in another function as an argument

Question 26

Besides adding an event listener callback function to an element or the document, what is one way to delay the execution of a JavaScript function until some point in the future?

Answer 26

using the setTimeout() global function

Question 27

How can you set up a function to be called repeatedly without using a loop?

Answer 27

using the setInterval() global function

Question 28

What is the default time delay if you omit the delay parameter from setTimeout() or setInterval()?

Answer 28

default is 0 milliseconds

Question 29

What do setTimeout() and setInterval() return?

Answer 29

returns a unique timeoutID number only associated with that particular instance. can use the same timeoutID in setTimeout() and setInterval() and clearInterval()

Question 30

What is a client?

Answer 30

requests services from a server

Question 31

What is a server?

Answer 31

provides resources/ services to client

Question 32

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 32

GET

Question 33

What three things are on the start-line of an HTTP request message?

Answer 33

An HTTP method (a verb (like GET, PUT or POST) or a noun (like HEAD or OPTIONS)),
request target (usually a URL), and HTTP Version

Question 34

What three things are on the start-line of an HTTP response message?

Answer 34

protocol version, usually HTTP/1.1, A status code, (indicating success or failure of the request– usually 200, 404, 302), and status text (just information, doesnt change or add things, but more for human understanding)

Question 35

What are HTTP headers?

Answer 35

lets the client and the server pass additional information with HTTP request or response – ‘case insensitive name’: value

Question 36

Where would you go if you wanted to learn more about a specific HTTP Header?

Answer 36

mdn

Question 37

Is a body required for a valid HTTP request or response message?

Answer 37

no, can be blank

Question 38

What is AJAX?

Answer 38

a technique to load data into part of a page without having to reload the whole page.

Question 39

What does the AJAX acronym stand for?

Answer 39

asynchronous javascript and XML

Question 40

Which object is built into the browser for making HTTP requests in JavaScript?

Answer 40

XMLHttpRequest()

Question 41

What event is fired by XMLHttpRequest objects when they are finished loading the data from the server?

Answer 41

‘load’ event

Question 42

Bonus Question: An XMLHttpRequest object has an addEventListener() method just like DOM elements. How is it possible that they both share this functionality?

Answer 42

they both are capable of handling/supporting events