Q
How do you declare a variable with an undefined value?

Answer & Solution

Answer: Option A
Solution:
Declaring a variable without assigning a value to it initializes it with undefined.
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What will typeof NaN return?

A). number

B). NaN

C). undefined

D). object

What will typeof [1, 2, 3] return?

A). array

B). object

C). number

D). list

Which method can be used to convert a string to a number in JavaScript?

A). parseInt()

B). toString()

C). toNumber()

D). parseStr()

What is the data type of an array in JavaScript?

A). Array

B). Object

C). Collection

D). List

Which of the following is not a primitive data type in JavaScript?

A). String

B). Number

C). Object

D). Boolean

Which operator checks both value and type for equality in JavaScript?

A). ==

B). !=

C). ===

D). !==

What is the output of '5' - 3?

A). 2

B). 2

C). 53

D). Error

What is the result of null === undefined?

A). 1

B). 0

C). Error

D). NaN

What is the output of typeof null?

A). null

B). undefined

C). object

D). number

What is the data type of true in JavaScript?

A). String

B). Boolean

C). Number

D). Object