JavaScript

Question 1

What is a variable?

Answer 1

container to store data

Question 2

What is a string?

Answer 2

characters

Question 3

What is the difference when it comes to using single quotes or double quotes ( ‘ ‘ or “ “ )?

Answer 3

nothing

Question 4

How do you escape quotation characters?

Answer 4

\

Question 5

What is type coercion?

Answer 5

converting type

Question 6

What is a number in JavaScript?

Answer 6

a data type

Question 7

What is an arithmetic operator?

Answer 7

mathematical function

Question 8

Name four of the arithmetic operators?

Answer 8

+ - * / %

Question 9

Why is the typeof an object null?

Answer 9

object

Question 10

What is the difference between null and undefined?

Answer 10

null is assigned null

undderfined is no assigned value

Question 11

Why do you always use === for comparisons?

Answer 11

to make sure data type are same

eg 0 is a falsy value but ‘0’is truthy

Question 12

What is the difference between undefined and null?

Answer 12

undefined is never assigned value;

null use to assign variable is needed to represent no value

Question 13

What is a function?

Answer 13

a group of statement to do some special task.

Question 14

Why are functions useful?

Answer 14

templating reusable

Question 15

How do you call a function?

Answer 15

Function name with parentheses and argument

Question 16

What are the parts of a function definition?

Answer 16

Function Keyword
Function Name 
Parameter
Code Block
Return inside Code Block

Question 17

What is the difference between a parameter and an argument?

Answer 17

parameter is part of function definition

argument is the value to pass in when call the function

Question 18

Why are variables useful?

Answer 18

remember value, store data

Question 19

What two special characters can a variable begin with?

Answer 19

$ _

Question 20

How do you declare a variable?

Answer 20

using variable keywords

var const let

Question 21

How do you assign a value to a variable?

Answer 21

assignment operator =

Question 22

Are variables case sensitive?

Answer 22

yes

Question 23

Which words cannot be used as variable names?

Answer 23

Reserved word

eg if function var while …

Question 24

Do all if statements require an else statement?

Answer 24

no

Question 25

What is an array in JavaScript?

Answer 25

An array is a special variable, which can hold more than one value at a time.

Question 26

How do you create an array literal?

Answer 26

var array = [ 1,2,3,4,5];

Question 27

What are the keys for the values inside an array?

Answer 27

numeric number from 0

Question 28

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

Answer 28

object;