Week 2 Quiz Questions

Question 1

What is the purpose of variables?

Answer 1

Variables are used to store temporary data (esp in scripts)

Question 2

How do you declare a variable?

Answer 2

Variable syntax:
var nameOfVariable = “string”
with var

Question 3

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

Answer 3

Variable syntax:
var nameOfVariable = “string”
with the equals sign (assignment operator)

Question 4

What characters are allowed in variable names?

Answer 4

letters, dollar signs, underscores, numbers.
cannot start with a number

Question 5

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

Answer 5

Upper and Lower case changes the variable you are using:
camelCase and camelcase would be different variables.

Question 6

What is the purpose of a string?

Answer 6

stores text data

Question 7

What is the purpose of a number?

Answer 7

used in counting/ calculating sums

Question 8

What is the purpose of a boolean?

Answer 8

has a value of true or false

Question 9

What does the = operator mean in JavaScript?

Answer 9

assignment operator used when assigning variables to a value

Question 10

How do you update the value of a variable?

Answer 10

declare the variable again (without var) and put the updated value on the other side of the assignment operator

Question 11

What is the difference between null and undefined?

Answer 11

null- variable that has no value
undefined- variable that has just been declared and doesnt have a value YET

Question 12

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

Answer 12

Shows user which variable/ object/ data type they are logging to the console. for neatness and clarity

Question 13

Give five examples of JavaScript primitives.

Answer 13

string, number, boolean, null, undefined.

Question 14

*

 and <style> similarities*</style>

Answer 14

CSS should be written in css files and console.log/js functions should be written in the js file
generally shouldnt (need to) write code within <style> and

</style>

Question 15

What data type is returned by an arithmetic operation?

Answer 15

number

Question 16

What is string concatenation?

Answer 16

combining two or more strings (or other primitive data types) into a new string that has both values combined

Question 17

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

Answer 17

in both arithmetic with numbers and string concatenation.

Question 18

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

Answer 18

boolean

Question 19

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

Answer 19

adds the value of the right operand to a variable and assigns the value to that same variable

Question 20

What are objects used for?

Answer 20

objects store sets of data (properties: keys and values, and methods: keys and functions)

Question 21

What are object properties?

Answer 21

a variable that is stored in an object (key: value pairs)

Question 22

Describe object literal notation.

Answer 22

var object = {
key: value
}

Question 23

How do you remove a property from an object?

Answer 23

with ‘delete’:
delete object.property

Question 24

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

Answer 24

can be used with either dot notation (object.dot) or bracket notation (object[“bracket”])

Question 25

What are arrays used for?

Answer 25

stores a (ordered) list of values (numbers, booleans, strings, arrays, objects)

Question 26

Describe array literal notation.

Answer 26

var array = [‘one’, 2, false]

Question 27

How are arrays different from “plain” objects?

Answer 27

Arrays, by nature, are ordered lists (and numerically indexed)

Question 28

What number represents the first index of an array?

Answer 28

0 (zero)

Question 29

What is the length property of an array?

Answer 29

Returns a numeric value of how many elements are in the array.
array.length = (some number)

Question 30

How do you calculate the last index of an array?

Answer 30

array.length - 1

Question 31

What is a function in JavaScript?

Answer 31

functions are sets of code that can be called/executed again after they have been created with a specific name and (sometimes) arguments.

Question 32

Describe the parts of a function definition.

Answer 32

function (keyword) functionName(parameter1, parameter2) { code block }

Question 33

Describe the parts of a function call.

Answer 33

functionName(argument1, argument2)

Question 34

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

Answer 34

function definition has the keyword ‘function’ and parameters instead of function call arguments. function definitions also have a code block that the call doesnt have, but executes.

Question 35

What is the difference between a parameter and an argument?

Answer 35

parameter used in the definition, arguments used in call

Question 36

Why are function parameters useful?

Answer 36

can provide more interact-able results when users/ programs put parameters in the function

give code more flexibility

Question 37

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

Answer 37

produces a value that can be used in our program and also exits the function/ code block the first instance the code runs into a return.

Question 38

Why do we log things to the console?

Answer 38

debug and make sure we know what data we are working with

Question 39

What is a method?

Answer 39

A method is a function which is a property of an object.

Question 40

How is a method different from any other function?

Answer 40

method is always directly associated with an object, a function operates on its own.

Question 41

How do you remove the last element from an array?

Answer 41

object.pop()

Question 42

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

Answer 42

Math.floor()

Question 43

How do you generate a random number?

Answer 43

Math.random()

Question 44

How do you delete an element from an array?

Answer 44

object.splice(location, delete location)
object.shift() beginning
object.pop() end

Question 45

How do you append an element to an array?

Answer 45

object.push() end
object.unshift() beginning

Question 46

How do you break a string up into an array?

Answer 46

object.split() puts split contents into array.

Question 47

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

Answer 47

no they don’t change– you can console.log() to check
primitives are immutable

Question 48

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

Answer 48

around 50 or so

Question 49

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

Answer 49

no, not always (object.pop() we might not need the popped item)

Question 50

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

Answer 50

around 40 or so

Question 51

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

Answer 51

MDN

Question 52

Give 6 examples of comparison operators.

Answer 52

<, <=, >, >=, ===

Question 53

What data type do comparison expressions evaluate to?

Answer 53

boolean (true/ false)

Question 54

What is the purpose of an if statement?

Answer 54

runs specific code if the condition is true

Question 55

Is else required in order to use an if statement?

Answer 55

no, not technically required, just code in if statement won’t run if conditions are not met

Question 56

Describe the syntax (structure) of an if statement.

Answer 56

if ( x ??? y) {
code block
}

Question 57

What are the three logical operators?

Answer 57

&&, ||, !

Question 58

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

Answer 58

use a logical operator depending on situation.

Question 59

What is the purpose of a loop?

Answer 59

execute a code block for a certain (or infinite) amount of times
good for arrays, objects.

Question 60

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

Answer 60

will run code block as long as condition returns true, quits the loop when condition is false

Question 61

What does “iteration” mean in the context of loops?

Answer 61

one complete execution of the code in the loop

Question 62

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

Answer 62

Before each pass of the loop. If returning false, loops stops.

Question 63

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

Answer 63

Once, before the loops begins

Question 64

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

Answer 64

Before each pass of the loop. If returning false, loops stops.

Question 65

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

Answer 65

after the code block is executed at the end of each pass

Question 66

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

Answer 66

break

Question 67

What does the ++ increment operator do?

Answer 67

adds by 1

Question 68

How do you iterate through the keys of an object?

Answer 68

for (x in object) { codeblock }

Question 69

What are the four components of “the Cascade”.

Answer 69

source order, inheritance, specificity, !important

Question 70

What does the term “source order” mean with respect to CSS?

Answer 70

the order in which css ruleset is written in a .css file. the last ruleset is the one that is applied if the specificity of all elements are the same

Question 71

How is it possible for the styles of an element to be applied to its children as well without an additional CSS rule?

Answer 71

certain child elements automatically inherit certain properties from the parent

Question 72

List the three selector types in order of increasing specificity.

Answer 72

type (h1, p, div, ::pseudo-element)
class (.myClass, [type=radio])
id (#myID)

Question 73

Why is using !important considered bad practice?

Answer 73

ignores specificity of elements and can cause difficulties in the future when wanting to target other selectors.