Answer & Solution
Answer: Option A
Solution:
The isNaN function determines if a value is NaN (Not-a-Number).
Q
What does the isNaN function do?
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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
Given the code: let y = 10; y = true;, what is the type of y after execution?
A). number
B). boolean
C). string
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Which of the following values is considered falsy in JavaScript?
A). 1
B). 0
C). 0
D). {}
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A). Number to String
B). String to Number
C). Boolean to String
D). Number to Boolean
Given let a = '10'; let b = 20;, what is the result of a + b?
A). 30
B). 1020
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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
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A). null
B). number
C). undefined
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What is the result of the following code: let x = 5; x = 'hello'; console.log(typeof x);?
A). number
B). string
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What is the result of typeof [] in JavaScript?
A). array
B). object
C). list
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What will typeof NaN return in JavaScript?
A). number
B). NaN
C). undefined
D). object