javascript

Question 1

What is the purpose of variables?

Answer 1

hold a value

Question 2

How do you declare a variable?

Answer 2

var

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

identifier must start with a letter, underscore ( _ ), or dollar sign ( $ ). Subsequent characters can also be digits ( 0 – 9 ).

Question 5

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

Answer 5

upper and lower case affects it

Question 6

What is the purpose of a string?

Answer 6

useful for holding data as text

Question 7

What is the purpose of a number?

Answer 7

primitive wrapper object used to represent and manipulate numbers

Question 8

What is the purpose of a boolean?

Answer 8

true or false

Question 9

What does the = operator mean in JavaScript?

Answer 9

assignment

Question 10

How do you update the value of a variable?

Answer 10

FIND THE ANSWER

Question 11

What is the difference between null and undefined?

Answer 11

undefined is a type, whereas null an object.

Question 12

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

Answer 12

to keep track of where you are

Question 13

Give five examples of JavaScript primitives

Answer 13

string, number, bigint, boolean, symbol, undefined

Question 14

What data type is returned by an arithmetic operation?

Answer 14

FIND THE ANSWER

Question 15

What is string concatenation?

Answer 15

method concatenates the string arguments to the calling string and returns a new string.

Question 16

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

Answer 16

addition or string concatenation

Question 17

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

Answer 17

find answer

Question 18

What are objects used for?

Answer 18

used to store keyed collections of various data and more complex entities

Question 19

What are object properties?

Answer 19

attributes linked with the property,

Question 20

Describe object literal notation.

Answer 20

An object initializer is a comma-delimited list of zero or more pairs of property names and associated values of an object, enclosed in curly braces ({}

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

find answer

Question 23

What are arrays used for?

Answer 23

store multiple values in a single variable

Question 24

Describe array literal notation.

Answer 24

list of expressions, each of which represents an array element, enclosed in a pair of square brackets ‘ [ ]

Question 25

How are arrays different from “plain” objects?

Answer 25

ordered list

Question 26

What number represents the first index of an array?

Answer 26

0

Question 27

What is the length property of an array?

Answer 27

shows how many entries

Question 28

How do you calculate the last index of an array?

Answer 28

array.length-1