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
Given let a = '10'; let b = 20;, what is the result of a + b?
A). 30
B). 1020
C). 30
D). NaN
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
Which operator is used to determine the type of a variable in JavaScript?
A). typeof
B). instanceof
C). type
D). isType
What is the type of the value returned by JSON.parse('null')?
A). null
B). string
C). object
D). undefined
What is the initial type of a variable declared with let a;?
A). null
B). number
C). undefined
D). object
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 type of the value returned by parseFloat('3.14abc')?
A). number
B). string
C). NaN
D). undefined
What will typeof NaN return in JavaScript?
A). number
B). NaN
C). undefined
D). object
In JavaScript, what will be the type of a variable x after x = 5 + true;?
A). number
B). string
C). boolean
D). undefined