Supreme Javascript Test - 63+ MCQs: JavaScript test: Assess Your Knowledge with JavaScript Questions and Answers

1. What is the purpose of the 'Math.random()' function in JavaScript?

Generates a random number between 0 and 1

Rounds a number to the nearest integer

Finds the square root of a number

Calculates the cosine of a number

2. How do you declare a variable in JavaScript?

let

var

const

all of the above

3. How do you comment in JavaScript?

// This is a comment

# This is a comment

/* This is a comment */

4. How do you check if an element has a specific class in JavaScript?

element.hasClass()

element.isClass()

element.containsClass()

element.classList.contains()

5. What is the purpose of the 'localStorage' object in JavaScript?

To store data permanently on the user's device

To access the internet

To handle user input

To create animations

6. Which of the following is a valid way to declare a JavaScript array?

var myArray = []

array myArray = []

new Array()

myArray = {}

7. Which method is used to add a class to an HTML element in JavaScript?

element.addClass()

element.classList.add()

element.addClassList()

element.addStyle()

8. What is the purpose of 'setTimeout()' in JavaScript?

Executes a function after a specified time

Pauses the execution of a function

Adds a delay to CSS animations

Sets an interval for a function

9. Which method is used to join elements of an array into a string in JavaScript?

join()

concat()

merge()

combine()

10. How do you declare a variable in JavaScript?

v myVar;

var myVar;

variable myVar;

let myVar;

11. What is the purpose of 'Promise' in JavaScript?

Handles asynchronous operations

Performs mathematical calculations

Creates an array of elements

Defines a function

12. Which of the following is a benefit of using JavaScript modules?

Encapsulation

Code Reusability

Dependency Management

All of the above

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

Number

Boolean

Undefined

Float

14. What is the purpose of the 'querySelector' method in JavaScript?

To select the first element that matches a specified CSS selector

To modify the structure of an HTML document

To create a new element

To retrieve data from a server

15. Which statement is used to exit a switch statement in JavaScript?

break

exit

return

end

16. What is the result of the expression '2' + 2 in JavaScript?

'22'

'4'

An error

17. What is the purpose of 'console.log()' in JavaScript?

Prints output to the console

Defines a new variable

Creates a loop

Imports a module

18. What does CSS stand for?

Counter Style Sheet

Computer Style Sheet

Colorful Style Sheet

Cascading Style Sheet

19. What is the purpose of the 'async' keyword in JavaScript?

To define a synchronous function

To handle exceptions

To indicate that a function returns a promise

To create an asynchronous loop

20. Which function is used to parse a JSON string in JavaScript?

parseJSON

evalJSON

JSON.parse

parseString

JavaScript MCQ Test 4