What happens when you try to access a variable that has not been declared in JavaScript?

What is the data type of the value undefined in JavaScript?

A). String

B). Object

C). Undefined

D). Number

What is the data type of the value NaN in JavaScript?

A). Number

B). String

C). Object

D). Undefined

What is a primitive value in JavaScript?

A). A complex data structure

B). A basic data type

C). A function

D). An array

Which of the following is a valid way to represent the value null in JavaScript?

A). undefined

B). NULL

C). null

D). None of the above

Which of the following is a valid JavaScript symbol?

A). symbol

B). &symbol

C). #symbol

D). Symbol('description')

What is the result of the expression 5 + '5' in JavaScript?

A). 10

B). '55'

C). '10'

D). Error

Which of the following is not a primitive value in JavaScript?

A). Number

B). Boolean

C). Object

D). String

What is the default value of a variable in JavaScript if it is not initialized?

A). null

B). undefined

C). 0

D). 'undefined'

Which of the following statements is true about primitive data types in JavaScript?

A). They have methods and properties

B). They can be used as keys in objects

C). They are instances of Object

D). They are passed by value

Which primitive value represents absence of value or no value assigned?

A). undefined

B). null

C). 0

D). 'undefined'