JavaScript MCQ Questions with answers and solutions Page 150

Q. What is the output of: console.log('5' + 3);

(A) 8
(B) 53
(C) NaN
(D) Error

✅ Correct Answer: (B) 53

Explanation: The + operator with a string and number results in string concatenation, so '5' + 3 = '53'.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:38 am in JavaScript

Q. What will be the output of the following code?

Code:

console.log(2 + '2');

(A) 4
(B) 22
(C) NaN
(D) Error

💬 Discuss

✅ Correct Answer: (B) 22

Explanation: JavaScript coerces the number 2 to a string and concatenates, resulting in '22'.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. How do you define an arrow function in JavaScript?

(A) function => {}
(B) () => {}
(C) () =>
(D) => () {}

💬 Discuss

✅ Correct Answer: (B) () => {}

Explanation: The correct syntax for an arrow function is: () => {}

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. What does '===' operator do in JavaScript?

(A) Assigns value
(B) Compares value and type
(C) Compares only value
(D) Checks if variable is defined

💬 Discuss

✅ Correct Answer: (B) Compares value and type

Explanation: '===' checks both value and data type for equality.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. Which built-in method reverses the elements of an array?

(A) flip()
(B) reverse()
(C) turn()
(D) back()

💬 Discuss

✅ Correct Answer: (B) reverse()

Explanation: The reverse() method reverses the order of array elements.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. What is the result of typeof NaN in JavaScript?

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

💬 Discuss

✅ Correct Answer: (A) number

Explanation: NaN is of type number in JavaScript, although it means Not-a-Number.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. Which of the following is not a JavaScript data type?

(A) Boolean
(B) Undefined
(C) Float
(D) Symbol

💬 Discuss

✅ Correct Answer: (C) Float

Explanation: JavaScript does not have a separate Float type; all numbers are of type Number.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. What will the following code print?

Code:

let a;
console.log(a);

(A) null
(B) undefined
(C) 0
(D) ReferenceError

💬 Discuss

✅ Correct Answer: (B) undefined

Explanation: A declared but uninitialized variable is 'undefined'.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. Which function is used to parse a string to an integer?

(A) parseInt()
(B) int()
(C) toInteger()
(D) Number.parse()

💬 Discuss

✅ Correct Answer: (A) parseInt()

Explanation: parseInt() is used to convert a string to an integer.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

Q. What will the output be?

Code:

let x = [1, 2, 3];
let y = x;
y.push(4);
console.log(x);

(A) [1, 2, 3]
(B) [1, 2, 3, 4]
(C) [4]
(D) undefined

💬 Discuss

✅ Correct Answer: (B) [1, 2, 3, 4]

Explanation: Arrays are reference types, so modifying y also affects x.

Published by Chandani ⭐ 10.97K Points at 14-Jun-2025 07:39 am in JavaScript

JavaScript MCQs with answers Page - 150

Q. What is the output of: console.log('5' + 3);

Q. What will be the output of the following code?

Q. How do you define an arrow function in JavaScript?

Q. What does '===' operator do in JavaScript?

Q. Which built-in method reverses the elements of an array?

Q. What is the result of typeof NaN in JavaScript?

Q. Which of the following is not a JavaScript data type?

Q. What will the following code print?

Q. Which function is used to parse a string to an integer?

Q. What will the output be?

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