What does the isNaN function do?

Which operator is used to determine the type of a variable in JavaScript?

A). typeof

B). instanceof

C). type

D). isType

What does the parseInt function do in JavaScript?

A). Converts a number to a string

B). Converts a string to an integer

C). Converts a boolean to a number

D). Converts an array to a number

In JavaScript, what will be the type of a variable x after x = 5 + true;?

A). number

B). string

C). boolean

D). undefined

What will be the result of the following code: let z = '123'; z = Number(z); console.log(typeof z);?

A). string

B). number

C). undefined

D). boolean

What will typeof null return in JavaScript?

A). null

B). undefined

C). object

D). number

What does it mean that JavaScript is dynamically typed?

A). Variables do not have types

B). Variables can change type

C). Variables must be declared with a type

D). Variables cannot change type

How can you check if a variable is an array in JavaScript?

A). typeof variable === 'array'

B). Array.isArray(variable)

C). variable instanceof array

D). variable.constructor === array

What happens when you add a number and a string in JavaScript?

A). An error is thrown

B). The number is converted to a string

C). The string is converted to a number

D). Both are converted to boolean

Given let a = '10'; let b = 20;, what is the result of a + b?

A). 30

B). 1020

C). 30

D). NaN

What is the result of typeof [] in JavaScript?

A). array

B). object

C). list

D). undefined