JavaScript MCQs with answers Page - 151

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. Which of these is a valid JavaScript variable name?

  • (A) 1value
  • (B) $value
  • (C) var
  • (D) -value

A

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Q. Which keyword is used for inheritance in ES6 classes?

  • (A) extends
  • (B) implements
  • (C) inherits
  • (D) derive

A

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Q. What will this output?

Code:
console.log(typeof function(){});
  • (A) object
  • (B) function
  • (C) undefined
  • (D) string

A

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Q. How can you prevent a variable from being reassigned?

  • (A) Use var
  • (B) Use let
  • (C) Use const
  • (D) Use strict

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Q. What will the following code return?

Code:
let x = 0;
if (x) { console.log('true'); } else { console.log('false'); }
  • (A) true
  • (B) false
  • (C) undefined
  • (D) 0

A

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Q. Which method checks if an array contains a certain value?

  • (A) has()
  • (B) contains()
  • (C) includes()
  • (D) exists()

A

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Q. What will be the result?

Code:
const obj = {name: 'John'};
delete obj.name;
console.log(obj.name);
  • (A) undefined
  • (B) John
  • (C) null
  • (D) Error

A

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Q. What is the default return value of a function with no return statement?

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

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Q. What will be logged?

Code:
console.log(typeof []);
  • (A) array
  • (B) object
  • (C) undefined
  • (D) list

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Q. Which statement is used to exit a loop early?

  • (A) exit
  • (B) continue
  • (C) stop
  • (D) break

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