javascript

Question 1

What is the purpose of variables?

Answer 1

to store data for the future

Question 2

How do you declare a variable?

Answer 2

use a variable keyword to declare the variable then a variable name

“var poopy”

Question 3

How do you initialize (assign a value to) a variable?

Answer 3

use a =

Question 4

What characters are allowed in variable names?

Answer 4

letters, underscores, $, numbers can be used but NOT in the front

Numbered variable names are CRINGE

Question 5

What does it mean to say that variable names are “case sensitive”?

Answer 5

Score =/= score

Question 6

What is the purpose of a string?

Answer 6

way to hold a sequence of characters - preserve text without freaking js out

Question 7

What is the purpose of a number?

Answer 7

calculations, MATHS

Question 8

What is the purpose of a boolean?

Answer 8

use it to make a choice

Question 9

What does the = operator mean in JavaScript?

Answer 9

to assign variables things

Question 10

How do you update the value of a variable?

Answer 10

var name then assign it to another variable, no keyword

Question 11

What is the difference between null and undefined?

Answer 11

null - intentional absence of a value - it can be defined

undefined - bad - empty that comes from JS. it says “theres nothing here” - means you fucked up

Question 12

Why is it a good habit to include “labels” when you log values to the browser console?

Answer 12

otherwise you don’t know what the console log is for

Question 13

Give five examples of JavaScript primitives

Answer 13

string, number, boolean, undefined, null

Question 14

What data type is returned by an arithmetic operation?

Answer 14

number

Question 15

What is string concatenation?

Answer 15

taking any type of values. that get added to a string, and it all becomes a string.

Question 16

What purpose(s) does the + plus operator serve in JavaScript?

Answer 16

math and concatenate

Question 17

What data type is returned by comparing two values (<, >, ===, etc)?

Answer 17

boolean

Question 18

What does the += “plus-equals” operator do?

Answer 18

they dbz fusion into gotenks

Question 19

What are objects used for?

Answer 19

group together variables/properties

what if i need info on more than 1 dog???

Question 20

What are object properties?

Answer 20

key + value inside the object

the word & the definition in the dictionary

Question 21

Describe object literal notation.

Answer 21

an array of key:value pairs with a comma inbetween, except for the last

Question 22

How do you remove a property from an object?

Answer 22

delete operator

Question 23

What are the two ways to get or update the value of a property?

Answer 23

brackets or dot for get, same for update

Question 24

What are arrays used for?

Answer 24

good for lists of stuff at any length

the order is either EXTREMELY important, or doesn’t matter

Question 25

Describe array literal notation.

Answer 25

brackets baybee with any data type inside

Question 26

How are arrays different from "plain" objects?

Answer 26

all arrays have a length property, even []

Question 27

What number represents the first index of an array?

Answer 27

0, big fat zero

Question 28

What is the length property of an array?

Answer 28

how long the array is

Question 29

How do you calculate the last index of an array?

Answer 29

array.length minus 1

Question 30

What is a function in JavaScript?

Answer 30

a set of stuff that performs a task

Question 31

Describe the parts of a function definition.

Answer 31

inputs outputs rules, (), {}, function name, parameters, keywords, etc etc etc var const let for while do

Question 32

Describe the parts of a function call.

Answer 32

arguments parameters function name

Question 33

When comparing them side-by-side, what are the differences between a function call and a function definition?

Answer 33

define makes the function call runs it, calls have no {}

Question 34

What is the difference between a parameter and an argument?

Answer 34

arguments are values provided when function is called parameters are placeholder names for when function is defined

Question 35

Why are function parameters useful?

Answer 35

its a placeholder and kinda a formula for later

Question 36

What two effects does a return statement have on the behavior of a function?

Question 37

Give 6 examples of comparison operators.

Question 38

What data type do comparison expressions evaluate to?

Answer 38

boolean

Question 39

What is the purpose of an if statement?

Answer 39

it allows us to make conditions

Question 40

Is else required in order to use an if statement?

Answer 40

no

Question 41

Describe the syntax (structure) of an if statement.

Answer 41

if (conditon) {stuff happens}

Question 42

What are the three logical operators?

Answer 42

&&, ||, !

Question 43

How do you compare two different expressions in the same condition?

Answer 43

&&, ||

Question 44

Why do we log things to the console?

Answer 44

to see wtf is happening, debugging

Question 45

What is a method?

Answer 45

actions performed on objects

Question 46

How is a method different from any other function?

Answer 46

methods are associated with objects functions are NOT

Question 47

How do you remove the last element from an array?

Answer 47

object.pop() pop method

Question 48

How do you round a number down to the nearest integer?

Answer 48

math.floor()

Question 49

How do you generate a random number?

Answer 49

math.random() random method of the math object it gives you 0 - .999999999999999999, then u multiply by whatev u need to get the rando # u need

Question 50

How do you delete an element from an array?

Answer 50

splice method

Question 51

How do you append an element to an array?

Answer 51

push generally we add things to ends of arrays

Question 52

How do you break a string up into an array?

Answer 52

split

Question 53

Do string methods change the original string? How would you check if you weren't sure?

Answer 53

console log it yes

Question 54

Is the return value of a function or method useful in every situation?

Answer 54

naw

Question 55

What three-letter acronym should you always include in your Google search about a JavaScript method or CSS property?

Answer 55

MDN

Question 56

What is the purpose of a loop?

Answer 56

allows you t odo the same t'hing over and over wtihout having to write a lot of code. repeat same codeblock over and over until a condition is met

Question 57

What is the purpose of a condition expression in a loop?

Answer 57

the condition is the breaks. How do we stop the loop?

Question 58

What does "iteration" mean in the context of loops?

Answer 58

every single pass thru of the loop code block

Question 59

When does the condition expression of a while loop get evaluated?

Answer 59

before executing the iteration/codeblock

Question 60

When does the initialization expression of a for loop get evaluated?

Answer 60

it happens once, before anything.

Question 61

When does the condition expression of a for loop get evaluated?

Answer 61

after initialization, and every time it repeats (before iterations)

Question 62

When does the final expression of a for loop get evaluated?

Answer 62

end of each loop iteration

Question 63

Besides a return statement, which exits its entire function block, which keyword exits a loop before its condition expression evaluates to false?

Answer 63

break - good for if you're tryna find 1 value in an array or something

Question 64

What does the ++ increment operator do?

Question 65

How do you iterate through the keys of an object?

Answer 65

for key in object

Question 66

What is JSON?

Answer 66

text based data format

Question 67

What are serialization and deserialization?

Answer 67

converts object into string deserial converts string into object

Question 68

Why are serialization and deserialization useful?

Question 69

How do you serialize a data structure into a JSON string using JavaScript?

Answer 69

json dot parse

Question 70

How do you deserialize a JSON string into a data structure using JavaScript?

Question 71

What is a method?

Answer 71

a function which is a property of an object

Question 72

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

Answer 72

has the codeblock, call does not

Question 73

Describe method definition syntax (structure).

Answer 73

objects property: (function parameters) {codeblock}

Question 74

Describe method call syntax (structure).

Answer 74

object.method (arguments)

Question 75

How is a method different from any other function?

Answer 75

it's defined in an object, there's object . _____

Question 76

What is the defining characteristic of Object-Oriented Programming?

Answer 76

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

Question 77

What are the four "principles" of Object-Oriented Programming?

Answer 77

abstraction, encapsulation, inheritance, polymorphism

Question 78

What is "abstraction"?

Answer 78

being able to work with complex systems, but in simple ways

Question 79

What does API stand for?

Answer 79

application programming interface

Question 80

What is the purpose of an API?

Answer 80

a way for 2 or more computers to interact with each other

Question 81

What is this in JavaScript?

Answer 81

the value of this is determined by how a function is called (runtime binding). It can't be set by assignment during execution, and it may be different each time the function is called.

Question 82

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

Question 83

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

Answer 83

call time

Question 84

How can you tell what the value of this will be for a particular function or method definition?

Question 85

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

Question 85

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