JavaScript MCQs with answers Page - 140

Here, you will find a collection of MCQ questions on JavaScript. Go through these questions to enhance your preparation for upcoming examinations and interviews.

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Q. What will be the result of await Promise.reject('error') in async function?

  • (A) Unhandled rejection error
  • (B) Syntax error
  • (C) Code continues
  • (D) undefined

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Q. Which of the following is NOT a valid JavaScript class feature?

  • (A) private class variables using #
  • (B) static methods
  • (C) public class properties
  • (D) constructors overloading

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Q. Which object method executes a reducer function on each element?

  • (A) reduce()
  • (B) map()
  • (C) filter()
  • (D) sort()

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Q. What will console.log(typeof []) return?

  • (A) object
  • (B) array
  • (C) list
  • (D) function

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Q. What is the result of 2 + '2'?

  • (A) 22
  • (B) 4
  • (C) undefined
  • (D) NaN

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Q. Which feature allows defining class-level methods?

  • (A) static
  • (B) global
  • (C) const
  • (D) private

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Q. How do you catch both resolved and rejected states of a Promise?

  • (A) then().catch()
  • (B) catch().then()
  • (C) done().fail()
  • (D) async()

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Q. Which method ensures code runs regardless of Promise result?

  • (A) finally()
  • (B) always()
  • (C) resolve()
  • (D) done()

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Q. What is the event loop in JavaScript?

  • (A) A mechanism that handles asynchronous callbacks
  • (B) A loop used to iterate over DOM elements
  • (C) A function that repeats code
  • (D) A type of loop like for or while

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Q. Which queue does setTimeout use?

  • (A) macrotask queue
  • (B) microtask queue
  • (C) callback queue
  • (D) event queue

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