What does the isNaN function do?
A). Checks if a value is not a number
B). Converts a value to a number
C). Checks if a value is a number
D). Converts a value to NaN
In JavaScript, what will be the type of a variable x after x = 5 + true;?
A). number
B). string
C). boolean
D). undefined
What is the result of the following code: let x = 5; x = 'hello'; console.log(typeof x);?
A). number
B). string
C). undefined
D). object
What is the type of the value returned by JSON.parse('null')?
A). null
B). string
C). object
D). undefined
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 is the initial type of a variable declared with let a;?
A). null
B). number
C). undefined
D). object
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
Given the code: let y = 10; y = true;, what is the type of y after execution?
A). number
B). boolean
C). string
D). object
Given let a = '10'; let b = 20;, what is the result of a + b?
A). 30
B). 1020
C). 30
D). NaN
What will typeof NaN return in JavaScript?
A). number
B). NaN
C). undefined
D). object