JavaScript

Question 1

what is a variables?

Answer 1

a variable is a something that holds a value

Question 2

Why are variables useful?

Answer 2

as a reference, to go and get that data

Question 3

What two special characters can a variable begin with?

Answer 3

$ dollar sign and _ underscore

Question 4

How do you declare a variable?

Answer 4

the var keyword

Question 5

How do you assign a value to a variable?

Answer 5

= known as the assignment operator or equal sign

Question 6

Are variables case sensitive?

Answer 6

Yes

Question 7

Which words cannot be used as variable names?

Answer 7

function, var, if, else, switch, no numbers at the beginning. Basically keywords

Question 8

What is a string?

Answer 8

sub series of characters enclosed by quotes

Question 9

What is the string concatenations operator?

Answer 9

the plus sign

Question 10

What is the difference when it comes to using single quotes or double quotes?

Answer 10

nothing

Question 11

How do you escape quotations characters?

Answer 11

\ backslash

Question 12

What is type coercion?

Answer 12

converting value from one type to another

Question 13

What is a number in Javascript?

Answer 13

a data type

Question 14

What is an arithmetic operator

Answer 14

math function that takes two operands and performs a calculation on them

Question 15

Name four of the arithmetic operators

Answer 15

+ - * /

Question 16

What is the order of execution?

Answer 16

(PEMDAS) mult and div before add and sub

Question 17

What is a boolean?

Answer 17

true or false data type

Question 18

What is a comparison operator?

Answer 18

comparing values to each other and resolve to a boolean

Question 19

What is the difference between undefined and null?

Answer 19

humans assign null and undefined is accidental

Question 20

What is a function?

Answer 20

block of code designed to perform a particular task

Question 21

Why are functions useful?

Answer 21

to be more productive

Question 22

How do you call a function?

Answer 22

with a parenthesis ()

Question 23

What are the parts of a function definition?

Answer 23

function keyword, parameter list, code block, return

Question 24

What is the difference between a parameter and an argument?

Answer 24

parameter is a named variable passed into a function, argument are the actual values passed to the function

Question 25

Why is it important to understand truthy and falsy values?

Answer 25

to check conditionals

Question 26

Why is the typeof an object null?

Answer 26

its a bug

Question 27

What is the difference between null and undefined?

Answer 27

null is an assigned value and undefined means a variable has been declared but not defined yet

Question 28

Why do you always use === for comparisons?

Answer 28

to not allow multiple different types of values or to make it more strict

Question 29

Why do you want to avoid using == for comparison?

Answer 29

to not have variance in the code

Question 30

Do all if statements require an else statement/

Answer 30

NO

Question 31

What is the proper syntax for using the or operator?

Answer 31

|| dual pipes

Question 32

What is the primary use case for switches?

Answer 32

allows a variable to be tested for equality against a list of values

Question 33

Does the default case have to be a at the bottom of the switch statement?

Answer 33

it can be at any place within the switch

Question 34

What happens if there is no break statement between cases?

Answer 34

the program continues to the next labeled statement.

Question 35

What is an object in JS?

Answer 35

unordered collection of related data. a collection of properties and methods linked together

Question 36

How do you create an object literal?

Answer 36

var object ={ };
var object = new Object( );
its the same thing

Question 37

What is a property in relation to JS objects?

Answer 37

A place in which we store data inside on an object.

Question 38

When should you use bracket notation over dot notation with objects?

Answer 38

bracket notations allows the use of characters that can’t be used with dot notation. Also when a property name is a variable

Question 39

How do you remove a property from an object?

Answer 39

the delete operator deletes both the value of the property and the property itself.

Question 40

What is an array?

Answer 40

used to store a collection of data

Question 41

How do you create an array literal?

Answer 41

by using an enclosed square bracket

Question 42

What are the keys for the values inside an array?

Answer 42

numbers counting up from zero

Question 43

Arrays have a property named length. Because arrays have properties, what other data structure are they similar to?

Answer 43

objects

Question 44

What are some good use cases for using objects inside arrays?

Answer 44

to remember the order of a series of objects. anything that involves a list of complex data