JavaScript MCQ Questions with answers and solutions Page 154

Q. What does this function return?

Code:

function test() {
  return typeof arguments;
}

(A) "arguments"
(B) "array"
(C) "object"
(D) "function"

💬 Discuss

✅ Correct Answer: (C) "object"

Explanation: arguments is an array-like object, and typeof returns 'object'.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. Which one is not a primitive data type in JavaScript?

(A) string
(B) object
(C) number
(D) boolean

💬 Discuss

✅ Correct Answer: (B) object

Explanation: object is not a primitive data type; it's a complex type.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. What is the output of this expression?

Code:

console.log('5' + 1);

(A) 6
(B) '51'
(C) undefined
(D) NaN

💬 Discuss

✅ Correct Answer: (B) '51'

Explanation: String + number results in string concatenation in JavaScript.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. How do you write an arrow function that returns 10?

(A) () => return 10;
(B) () => 10
(C) => 10
(D) function => 10

💬 Discuss

✅ Correct Answer: (B) () => 10

Explanation: Arrow functions return the value of a single expression without braces.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. What does the rest operator do?

(A) Copies arrays
(B) Spreads arrays
(C) Collects remaining arguments
(D) None of the above

💬 Discuss

✅ Correct Answer: (C) Collects remaining arguments

Explanation: The rest operator (...) collects remaining parameters into an array.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. What will this log?

Code:

console.log(typeof NaN);

(A) "NaN"
(B) "number"
(C) "undefined"
(D) "object"

💬 Discuss

✅ Correct Answer: (B) "number"

Explanation: NaN is considered a number in JavaScript.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. Which method can be used to iterate over an array?

(A) forEach()
(B) map()
(C) for...of
(D) All of the above

💬 Discuss

✅ Correct Answer: (D) All of the above

Explanation: All listed options can be used to iterate over arrays.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. What does this code do?

Code:

setTimeout(() => console.log('Hello'), 0);

(A) Logs immediately
(B) Logs after 0 ms delay
(C) Never logs
(D) Throws error

💬 Discuss

✅ Correct Answer: (B) Logs after 0 ms delay

Explanation: Even with 0 ms, the function is added to the event queue.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. What is the result of this?

Code:

false == '0';

(A) true
(B) false
(C) undefined
(D) Error

💬 Discuss

✅ Correct Answer: (A) true

Explanation: Loose equality allows coercion, and false == '0' is true.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

Q. Which keyword creates a constant in JavaScript?

(A) let
(B) constant
(C) const
(D) define

💬 Discuss

✅ Correct Answer: (C) const

Explanation: const is used to declare constants.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:40 am in JavaScript

JavaScript MCQs with answers Page - 154

Q. What does this function return?

Q. Which one is not a primitive data type in JavaScript?

Q. What is the output of this expression?

Q. How do you write an arrow function that returns 10?

Q. What does the rest operator do?

Q. What will this log?

Q. Which method can be used to iterate over an array?

Q. What does this code do?

Q. What is the result of this?

Q. Which keyword creates a constant in JavaScript?

Programming Categories

📱 Download Our App