Variables

Question 1

What is let ?

Answer 1

One of the keyword used when you want to declare a variable that is might be reassigned

Question 2

What is const ?

Answer 2

One of the keyword used when you want to declare a variable with a constant value

Question 3

What are the keywords possible for a variable?

Answer 3

Var : used pre-ES6 versions of JS
Let : variable can be reassigned a different value
Const : variable cannot be reassigned because it is constant

Question 4

What happens when a variable has not been initialized ?

Answer 4

The primitive data type is going to be store undefined

Question 5

What happens if you try to reassign a
const variable?

Answer 5

You’ll get aTypeError

Question 6

What happens if you try to declare aconstvariable without a value?

Answer 6

You’ll get aSyntaxError

Question 7

When do you get aSyntaxError?

Answer 7

If you try to declare a const variable without a value

Question 8

When do you get a TypeError?

Answer 8

If you try to reassign aconstvariable

Question 9

When do you get automatically a value ofundefined?

Answer 9

If we don’t assign a value to a variable declared using theletkeyword

Question 10

What happens If we don’t assign a value to a variable declared using theletkeyword?

Answer 10

It automatically has a value of undefined

Question 11

What are the few general rules for naming variables?

Answer 11

• Variable names cannot start with numbers.
• Variable names are case sensitive, somyNameandmynamewould be different variables. It is bad practice to create two variables that have the same name using different cases.
• Variable names cannot be the same askeywords.

Question 12

What is = ?

Answer 12

An assignment operator

Question 13

What is what ?
var myName =’Arya’;

Answer 13

1. var, short for variable, is a JavaScriptkeywordthat creates, ordeclares, a new variable.
2. myNameis the variable’s name.
3. =is theassignment operator. It assigns the value ('Arya') to the variable (myName).
4. 'Arya'is thevalueassigned (=) to the variablemyName

Question 14

What is a variable?

Answer 14

Avariableis a container for a value.
Variables also provide a way of labeling data with a descriptive name, so our programs can be understood more clearly by the reader and ourselves.
In short, variables label and store data in memory

Question 15

What can you do with variables ?

Answer 15

1. Create a variable with a descriptive name.
2. Store or update information stored in a variable.
3. Reference or “get” information stored in a variable.

Question 16

What are NOT variables?

Answer 16

Variables are not values

Question 17

What is var ?

Answer 17

Var : used pre-ES6 versions of JS
Short for variable, is a JavaScriptkeywordthat creates, ordeclares, a new variable.

Question 18

What is the increment operator ?

Answer 18

It’s ++

Question 19

What is the decrement operator ?

Answer 19

It’s –

Question 20

What are The Increment and Decrement Operator?

Answer 20

They are two of mathematical assignment operators. You can use them to update the variable’s valueandassigned as the new value of that variable.
Increment operator is (++)
Decrement operator is(–).

Question 21

Mathem

Answer 21

We can use variables and math operators to calculate new values and assign them to a variable

Question 22

How can we use the + operator?

Answer 22

The+operator is used to concatenate strings including string values held in variables.

Question 23

What do you use to interpolate values into a string ?

Answer 23

Template literals use backticks`and${}

Question 24

What is thetypeofkeyword for ?

Answer 24

Returns the data type (as a string) of a value.