JAVASCRIPT

Question 1

What is the purpose of variables?

Answer 1

to store or remmeber information

Question 2

How to declare a variable

Answer 2

var and name of variable

Question 3

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

Answer 3

=

Question 4

What characters are allowed in variable names?

Answer 4

$, any character, _, a number as long as its not in the beginning

Question 5

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

Answer 5

that capital letters affect it

Question 6

How do you update the value of a variable?

Answer 6

re declare them

Question 7

What is the difference between null and undefined?

Answer 7

null is put there by a programmer undefined is there in the absence of anything

Question 8

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

Answer 8

for readability

Question 9

What data type is returned by an arithmetic operation?

Answer 9

number

Question 10

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

Answer 10

concatination and addition

Question 11

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

Answer 11

boolean type

Question 12

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

Answer 12

adds the value to the current value and reasign the variable

Question 13

What are objects used for?

Answer 13

to combine like information

Question 14

What are object properties?

Answer 14

allow you to store information

Question 15

Describe object literal notation.

Answer 15

var object ={}

Question 16

How do you remove a property from an object?

Answer 16

delete operator

Question 17

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

Answer 17

. or []

Question 18

What are arrays used for?

Answer 18

store a list of items

Question 19

Describe array literal notation.

Answer 19

var array =[];

Question 20

How are arrays different from “plain” objects?

Answer 20

objects have properties arrays don’t

Question 21

What number represents the first index of an array?

Answer 21

0

Question 22

What is the length property of an array?

Answer 22

the number of values in array

Question 23

How do you calculate the last index of an array?

Answer 23

length -1

Question 24

What is a function in JavaScript?

Answer 24

an set of instructions

Question 25

Describe the parts of a function definition.

Answer 25

function name (parameter){code block}

Question 26

Describe the parts of a function call.

Answer 26

name of function and argument

Question 27

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

Answer 27

function definition defines the function. function call is calling the function

Question 28

What is the difference between a parameter and an argument?

Answer 28

parameter is just to hold value and has no value. | argument has a value.

Question 29

Why are function parameters useful?

Answer 29

it can be re used with different arguments

Question 30

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

Answer 30

it will return code outside of the function, and stops code from running after it

Question 31

Why do we log things to the console?

Answer 31

to debug

Question 32

What is a method?

Answer 32

a pre defined function which is a property of an object

Question 33

How is a method different from any other function?

Answer 33

you can only input arguments on methods, you can modify functions and how they work

Question 34

How do you remove the last element from an array?

Answer 34

.pop()

Question 35

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

Answer 35

Math.floor()

Question 36

How do you generate a random number?

Answer 36

Math.random()

Question 37

How do you delete an element from an array?

Answer 37

splice

Question 38

How do you break a string up into an array?

Answer 38

split

Question 39

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

Answer 39

no strings are immutable console.log

Question 40

Roughly how many string methods are there according to the MDN Web docs?

Answer 40

30

Question 41

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

Answer 41

depends not every situation

Question 42

Roughly how many array methods are there according to the MDN Web docs?

Answer 42

30ish

Question 43

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

Answer 43

mdn

Question 44

What data type do comparison expressions evaluate to?

Answer 44

boolean types

Question 45

What is the purpose of an if statement?

Answer 45

to make a decision

Question 46

Is else required in order to use an if statement?

Answer 46

no

Question 47

Describe the syntax (structure) of an if statement.

Answer 47

if (){}

Question 48

What are the three logical operators?

Answer 48

if, else, if else

Question 49

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

Answer 49

|| &&

Question 50

What is the purpose of a loop?

Answer 50

check condition and run code block multiple times

Question 51

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

Answer 51

the thing that says start or stop

Question 52

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

Answer 52

being repeated

Question 53

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

Answer 53

before each iteration

Question 54

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

Answer 54

before loop starts

Question 55

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

Answer 55

before initial iteration

Question 56

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

Answer 56

at the end after iteration

Question 57

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

Answer 57

break

Question 58

What does the ++ increment operator do?

Answer 58

increments by 1

Question 59

How do you iterate through the keys of an object?

Answer 59

for in loop

Question 60

what does the substr() method do

Answer 60

returns a portion of the string, starting at the specified index and extending for a given number of characters afterwards