JavaScript

Question 1

• What is the purpose of variables?

Answer 1

Stores data to be used later

Question 2

• How do youdeclarea variable?

Answer 2

keyword name = value;

Question 3

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

Answer 3

assignment operator

Question 4

• What characters are allowed in variable names?

Answer 4

anyletter, $ _ or number(cant be first character)

Question 5

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

Answer 5

the case sizing matters

Question 6

• What is the purpose of a string?

Answer 6

not code read by JS strings contain values to be saved as they are.

Question 7

• What is the purpose of a number?

Answer 7

used for math, or numeric values

Question 8

• What is the purpose of a boolean?

Answer 8

true or false, the logic of JS

Question 9

• How do you update the value of a variable?

Answer 9

name = value;

Question 10

• What is the difference betweennullandundefined?

Answer 10

null is intentionally assigned by programmer and is an intentional emptiness. Undefined is a JS assignment which declares a variable to have no arguments.

Question 11

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

Answer 11

to see what your console log is

Question 12

• Give five examples of JavaScript primitives.

Answer 12

boolean, null, undefined, string, number

Question 13

• What data type is returned by an arithmetic operation?

Answer 13

numbers

Question 14

• What is string concatenation?

Answer 14

combines words

Question 15

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

Answer 15

adds valuess and concatenates strings

Question 16

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

Answer 16

boolean

Question 17

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

Answer 17

adds values and assigns them

Question 18

What are objects used for?

Answer 18

create a model for information, like a phonebook

Question 19

what are object properties?

Answer 19

Obj {property: value}

Question 20

Object literal notation

Answer 20

{value, value,….};

Question 21

how do you remove a property from an object

Answer 21

delete operator

Question 22

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

Answer 22

dot notation or square brackets

Question 23

what are arrays used for

Answer 23

storing a list of information

Question 24

describe array literal notation

Answer 24

[value,value,….];

Question 25

how are arrays different from plain objects?

Answer 25

the properties are numeric

Question 26

first index of array

Answer 26

0

Question 27

how do you calculate the last index of an array?

Answer 27

array.length - 1

Question 28

What is a function in JavaScript?

Answer 28

a reusable group of tasks to return and receive different values.

Question 29

Describe the parts of a function

Answer 29

function name(parameters) {codeblock};

Question 30

describe the parts of a function call

Answer 30

name (arguments);

Question 31

• When comparing them side-by-side, what are the differences between a functioncalland a functiondefinition?

Answer 31

a definition has parameters, codeblock, keyword. A call has arguments.

Question 32

What is the difference between a parameter and argument?

Answer 32

the parameter is the placeholder for an argument.

Question 33

why are function parameters useful?

Answer 33

without them the function would do the same thing every time.

Question 34

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

Answer 34

exits the codeblock and gives back the value.

Question 35

what is a method?

Answer 35

function thats been saved into an object

Question 36

How is a method different from any other function?

Answer 36

Methods are functions stored into property of an object.

Question 37

remove the last element from an array

Answer 37

.pop();

Question 38

round a number down to the nearest integer?

Answer 38

Math.floor(); or Math.trunc();

Question 39

generate a random number

Answer 39

Math.random();

Question 40

delet an element from an array

Answer 40

.splice();

Question 41

append an element to an array

Answer 41

.push();

Question 42

break up a string into array?

Answer 42

.split();

Question 43

Do string methods change the original string? How can you check if unsure?

Answer 43

No, log the original string

Question 44

is the return value of a function useful in every situation?

Answer 44

No

Question 45

6 examples of comparison operators

Answer 45

> > = < <= === !==

Question 46

data type comparsion expressions evaluate to

Answer 46

boolean

Question 47

purpose of an if statement

Answer 47

add conditions to the code.

Question 48

is else required for proper if statement?

Answer 48

NO

Question 49

syntax of if statement

Answer 49

if (condition) {declaration};

Question 50

three logical operators

Answer 50

&& || !

Question 51

How do you compare two expressions in the same condition?

Answer 51

logical operator

Question 52

purpose of a loop

Answer 52

repeated block of code happening until the conditions stated are false

Question 53

Purpose of a condition expression

Answer 53

The brake of the loop, waiting until the boolean is false.

Question 54

what is an iteration in the context of loops?

Answer 54

one repetition of the loop.

Question 55

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

Answer 55

before each iteration

Question 56

when does the intialization expression of a for loop get evaluated?

Answer 56

it happens first, before anything else in the loop and it happens only once.

Question 57

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

Answer 57

after the intialization and it happens before each iteration

Question 58

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

Answer 58

at the end of each iteration and before the condition

Question 59

Besides areturnstatement, which exits its entire function block, which keyword exits a loop before itsconditionexpression evaluates tofalse?

Answer 59

break

Question 60

the ++ operator

Answer 60

adds 1

Question 61

how do you iterate through the keys of an object?

Answer 61

for in loop