50+ JavaScript MCQs with Answers (2023)
Looking for a comprehensive resource to test your knowledge of JavaScript? Look no further than our collection of 50+ multiple-choice questions with answers! Covering a wide range of topics including arrays, strings, loops, and more, this resource is perfect for anyone looking to brush up on their JavaScript skills. Whether you’re a beginner or an experienced developer, these questions will challenge your understanding and help you deepen your knowledge of this popular programming language.
What is JavaScript?
- A. A server-side language
- B. A client-side language
- C. Both A and B
- D. None of the above
Answer: B
Which of the following is not a data type in JavaScript?
- A. Boolean
- B. Integer
- C. String
- D. Object
Answer: B
What is the correct syntax for a JavaScript comment?
- A. //
- B. ##
- C. /
- D. %
Answer: A
What is the output of console.log(10 + “20”) in JavaScript?
- A. 1020
- B. 30
- C. 102
- D. Error
Answer: A
Which of the following is a built-in JavaScript function for converting a string to a number?
- A. parseInt()
- B. toString()
- C. parseFloat()
- D. stringify()
Answer: A
What is the correct way to declare a JavaScript variable?
- A. var x = 5;
- B. variable x = 5;
- C. x = 5;
- D. declare x = 5;
Answer: A
Which of the following is a JavaScript loop statement?
- A. for
- B. switch
- C. if
- D. else
Answer: A
What is the output of console.log(typeof null) in JavaScript?
- A. null
- B. undefined
- C. object
- D. number
Answer: C
Which of the following is a JavaScript comparison operator?
- A. ++
- B. **
- C. ==
- D. //
Answer: C
Which of the following is not a JavaScript logical operator?
- A. &&
- B. ||
- C. !
- D. #
Answer: D
What is the output of console.log(Math.floor(Math.random() * 10)) in JavaScript?
- A. A random number between 0 and 10
- B. A random number between 1 and 10
- C. A random number between 0 and 9
- D. A random number between 1 and 9
Answer: C
Which of the following is a JavaScript array method for adding an element to the end of an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: B
What is the output of console.log(“10” + 20 – 5) in JavaScript?
- A. 15
- B. 1020
- C. 25
- D. Error
Answer: B
What is the output of console.log(typeof NaN) in JavaScript?
- A. number
- B. NaN
- C. undefined
- D. object
Answer: A
Which of the following is a JavaScript function declaration?
- A. function myFunction() {}
- B. myFunction() {}
- C. var myFunction = function() {}
- D. All of the above
Answer: A
What is the output of console.log(2 + “2”) in JavaScript?
- A. “4”
- B. 4
- C. “22”
- D. Error
Answer: C
Which of the following is a JavaScript string method for converting a string to uppercase?
- A. toUpper()
- B. upperCase()
- C. toUpperCase()
- D. caseUpper()
Answer: C
What is the output of console.log(true || false) in JavaScript?
- A. true
- B. false
- C. null
- D. Error
Answer: A
What is the output of console.log(typeof []) in JavaScript?
- A. object
- B. array
- C. undefined
- D. Error
Answer: A
Which of the following is a JavaScript function for converting a number to a string?
- A. toString()
- B. parseInt()
- C. stringify()
- D. None of the above
Answer: A
What is the output of console.log(Math.ceil(4.3)) in JavaScript?
- A. 4
- B. 5
- C. 4.3
- D. Error
Answer: B
Which of the following is a JavaScript array method for removing the last element from an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: A
What is the output of console.log(10 > 5 && 5 < 4) in JavaScript?
- A. true
- B. false
- C. null
- D. Error
Answer: B
Which of the following is a JavaScript string method for finding the index of a specified character in a string?
- A. indexOf()
- B. charAt()
- C. slice()
- D. None of the above
Answer: A
What is the output of console.log(“hello”.length) in JavaScript?
- A. hello
- B. 5
- C. undefined
- D. Error
Answer: B
Which of the following is a JavaScript conditional statement?
- A. for
- B. switch
- C. if
- D. else
Answer: C
What is the output of console.log(typeof “hello”) in JavaScript?
- A. string
- B. object
- C. undefined
- D. Error
Answer: A
Which of the following is a JavaScript array method for reversing the order of the elements in an array?
- A. reverse()
- B. sort()
- C. concat()
- D. None of the above
Answer: A
What is the output of console.log(Math.pow(2, 3)) in JavaScript?
- A. 2
- B. 3
- C. 6
- D. 8
Answer: D
Which of the following is a JavaScript function for rounding a number to the nearest integer?
- A. ceil()
- B. floor()
- C. round()
- D. None of the above
Answer: C
What is the output of console.log(typeof true) in JavaScript?
- A. boolean
- B. object
- C. undefined
- D. Error
Answer: A
Which of the following is a JavaScript array method for adding an element to the beginning of an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: D
What is the output of console.log(“hello” + “world”) in JavaScript?
- A. “helloworld”
- B. “hello world”
- C. “hello+world”
- D. Error
Answer: A
Which of the following is a JavaScript function for generating a random number between 0 and 1?
- A. Math.random()
- B. Math.floor()
- C. Math.ceil()
- D. None of the above
Answer: A
What is the output of console.log(typeof undefined) in JavaScript?
- A. undefined
- B. object
- C. null
- D. Error
Answer: A
Which of the following is a JavaScript string method for removing whitespace from the beginning and end of a string?
- A. trim()
- B. slice()
- C. replace()
- D. None of the above
Answer: A
Which of the following is a JavaScript array method for sorting the elements in an array?
- A. reverse()
- B. sort()
- C. splice()
- D. None of the above
Answer: B
What is the output of console.log(“hello”.toUpperCase()) in JavaScript?
- A. hello
- B. Hello
- C. HELLO
- D. Error
Answer: C
Which of the following is a JavaScript function for converting a string to a number?
- A. toString()
- B. parseInt()
- C. parseFloat()
- D. None of the above
Answer: B
What is the output of console.log(typeof NaN) in JavaScript?
- A. number
- B. string
- C. undefined
- D. Error
Answer: A
Which of the following is a JavaScript array method for adding one or more elements to the end of an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: B
What is the output of console.log(10 === “10”) in JavaScript?
- A. true
- B. false
- C. null
- D. Error
Answer: B
Which of the following is a JavaScript function for finding the maximum value in an array?
- A. Math.min()
- B. Math.max()
- C. Array.min()
- D. Array.max()
Answer: B
What is the output of console.log(“hello”.charAt(0)) in JavaScript?
- A. h
- B. e
- C. l
- D. o
Answer: A
Which of the following is a JavaScript string method for replacing a specified character in a string with another character?
- A. replace()
- B. slice()
- C. concat()
- D. None of the above
Answer: A
What is the output of console.log(10 % 3) in JavaScript?
- A. 1
- B. 2
- C. 3
- D. Error
Answer: A
Which of the following is a JavaScript array method for removing elements from an array and replacing them with new elements?
- A. pop()
- B. push()
- C. splice()
- D. unshift()
Answer: C
What is the output of console.log(Math.floor(4.9)) in JavaScript?
- A. 4
- B. 5
- C. 4.9
- D. Error
Answer: A
Which of the following is a JavaScript loop statement for repeating a block of code as long as a specified condition is true?
- A. for loop
- B. while loop
- C. do…while loop
- D. switch statement
Answer: B
What is the output of console.log(“hello”.length) in JavaScript?
- A. hello
- B. 5
- C. null
- D. Error
Answer: B
Which of the following is a JavaScript function for generating a random number between 0 and 1?
- A. random()
- B. floor()
- C. ceil()
- D. None of the above
Answer: A
What is the output of console.log(10 + “10”) in JavaScript?
- A. 1010
- B. 20
- C. 101
- D. Error
Answer: A
Which of the following is a JavaScript array method for removing the last element from an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: A
What is the output of console.log(Math.pow(2, 3)) in JavaScript?
- A. 2
- B. 3
- C. 6
- D. 8
Answer: D
Which of the following is a JavaScript string method for extracting a section of a string and returning a new string?
- A. slice()
- B. replace()
- C. concat()
- D. None of the above
Answer: A
Which of the following is a JavaScript array method for removing the first element from an array?
- A. pop()
- B. push()
- C. shift()
- D. unshift()
Answer: C
What is the output of console.log(5 > 3 && 10 < 20) in JavaScript?
- A. true
- B. false
- C. null
- D. Error
Answer: A
