JS

Question 1

What is the command line?

Answer 1

Program in the computer that allows you to issue direct commands to the computer

Question 2

What is scope?

Answer 2

How accessible a variable is within your script

Question 3

What is a code block?

Answer 3

Anything within { }, except an object

Question 4

Local scope versus Global scope

Answer 4

In local scope, can access variables declared locally and globally. In global scope, can only access global variables

Question 5

What is data?

Answer 5

Data is a sequence of characters or symbols on which operations are performed by a computer

Question 6

What’s a data type?

Answer 6

Extra info about data that tells the computer how to deal with it and how to store it.

Question 7

What’s a program?

Answer 7

A series of instructions that perform a task, executed by a computer

Question 8

What are the data types of JavaScript?

Answer 8

1) string 2) number 3) boolean 4) null 5) undefined

6) object (a complex data type)

Question 9

Which value in JS is not strictly equal to itself and why?

Answer 9

NaN. Because NaN is like an undefinable number. NaN is unordered. It is not equal to, greater than or less than anything, including itself

Question 10

Loosely typed language means what?

Answer 10

JS is loosely typed in that it guesses what each data type is. JS does not require type declaration

Question 11

What is an API?

Answer 11

Application Programming Interface. It facilitates communication between a client and a server

Question 12

What is a server?

Answer 12

A computer program or device that accepts and responds to requests made by another program, often a client. A server manages network resources

Question 13

What is a client?

Answer 13

The opposite of a server. The thing that sends a request to a server

Question 14

What is a REST API?

Answer 14

REST is Representational State Transfer. A REST API follows a specific architectural style in how the data stored is arranged and how the API communicates with clients

Question 15

JSON and how it differs from JS.

Answer 15

JavaScript Object Notation. It has all the JavaScript data types except functions.

Question 16

What is Cache?

Answer 16

Hardware or software used to store something, often temporarily

Question 17

What is HTTP?

Answer 17

Hypertext Transfer Protocol. Its a set of rules through which browsers and servers communicate on the web

Question 18

What is an endpoint?

Answer 18

An API term. It’s the URL that points to the data in the API

Question 19

AJAX

Answer 19

Asynchronous JavaScript and XML. It’s a set of techniques using different web technologies on the client side to run asynchronous processes

Question 20

Asynchronous

Answer 20

Not at the same time. When something in the program is operating independently of other processes

Question 21

What are ‘props’ in react?

Answer 21

A prop is a property on a react element, and is represented as an object of its own properties which include the element’s content (children) and attributes like ‘id’, ‘src’, etc.

Question 22

Syntax parser

Answer 22

A program that reads your code and determines what it does, what it contains, and if its grammar is valid

Question 23

Lexical environment

Answer 23

It’s where something sits physically in the code. When lexical environment matters, it means that where you write something (eg. a variable) matters to the syntax parser.

Question 24

Execution context

Answer 24

A wrapper to help manage the code that is actually running

Question 25

An object

Answer 25

In JS, it’s a collection of name-value pairs.

Question 26

Global

Answer 26

Not inside a function

Question 27

What are the characteristics of Var?

Answer 27

Var declarations are 1) function scoped. They can be accessed anywhere within the function 2) can be redeclared with a new value 3) hoisted to the global object with the value of undefined.

Question 28

What are the characteristics of let?

Answer 28

1) Is block scoped {}. Only available and declared within the block. 2) can be reassigned ( actor = “chris pratt”) but NOT redeclared in the same scope (let actor = “ethan hawke”) 3) hoisted, but just the variable name - no value is provided unless you set one

Question 29

What are the characteristics of const

Answer 29

1) Block scoped (as is let). 2) Cannot be redeclared or reassigned. 3) If its an object however, the properties can be updated or reassigned

Question 30

What’s Babel?

Answer 30

It is an open source program that allows you to write ES6 code that is then made backwards compatible with older browsers

Question 31

What’s webpack?

Answer 31

It’s a bundler (or module builder) based in JavaScript that figures out all the dependencies in your code then puts together a minimalist version that can be plugged into your HTML file and run.

Question 32

The DOM

Answer 32

The DOM is an API for HTML (and XML documents). The DOM is a structural representation of your HTML document that allows you to interact with the document using JavaScript

Question 33

What are falsy values. Is an empty array truthy or falsey?

Answer 33

A falsy value in JS is a value that is considered ‘false’ when evaluated in a Boolean context.

The JS falsy values are: 0, null, undefined, “ “, false, NaN.

Everything else is truthy, including an empty array and empty object