JavaScript MCQs with answers Page - 149

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 is hoisting in JavaScript?

  • (A) Declaring variables at the top
  • (B) Using let and const only
  • (C) JavaScript's default behavior of moving declarations to the top
  • (D) None of the above

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Q. Which value is returned when a function doesn't explicitly return anything?

  • (A) null
  • (B) undefined
  • (C) false
  • (D) 0

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Q. How can you clone an object in JavaScript?

  • (A) Object.clone(obj)
  • (B) obj.copy()
  • (C) Object.assign({}, obj)
  • (D) clone(obj)

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Q. What does the 'await' keyword do?

  • (A) Pauses the function until a promise settles
  • (B) Pauses script execution globally
  • (C) Rejects promises
  • (D) Creates a new thread

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Q. What is the output?

Code: 
console.log(3 > 2 > 1);
  • (A) true
  • (B) false
  • (C) undefined
  • (D) NaN

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Q. What type is returned by Array.isArray([])?

  • (A) boolean
  • (B) string
  • (C) object
  • (D) undefined

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Q. Which method returns the first index of an element?

  • (A) search()
  • (B) findIndex()
  • (C) indexOf()
  • (D) find()

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Q. Which of the following is true about 'const'?

  • (A) Cannot be reassigned
  • (B) Cannot be mutated
  • (C) Not block-scoped
  • (D) Hoisted to top with undefined

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Q. What will this return?

Code: 
console.log('10' - '4' - '3' - 2 + '5');
  • (A) 15
  • (B) 1
  • (C) 15
  • (D) 15undefined

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Q. Which statement is true about let, var, and const?

  • (A) var is block scoped
  • (B) let is function scoped
  • (C) const must be initialized
  • (D) const can be reassigned

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