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

1. How do you comment in JavaScript?

// This is a comment

# This is a comment

/* This is a comment */

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

To generate a random number between 0 and 1

To round a number to the nearest integer

To perform a mathematical operation

To check if a number is even or odd

3. What is the purpose of the 'bind' method in JavaScript?

To bind an event handler to an element

To create a new array with the results of calling a provided function on every element in the array

To change the value of 'this' in a function

To filter elements in an array

4. What does the 'typeof' operator do in JavaScript?

Returns the type of a variable

Checks if a variable is defined

Concatenates strings

Compares two values

5. How do you declare a variable in JavaScript?

let

var

const

all of the above

6. Which method is used to remove the last element from an array in JavaScript?

pop()

push()

shift()

unshift()

7. Which method is used to change the content of an HTML element in JavaScript?

innerHTML

textContent

innerText

appendText

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

Selects an HTML element by its id

Applies styles to an element

Creates a new HTML element

Removes an element from the DOM

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

Prints output to the console

Defines a new variable

Creates a loop

Imports a module

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

Handles asynchronous operations

Performs mathematical calculations

Creates an array of elements

Defines a function

11. Which keyword is used to define a constant in JavaScript?

const

let

var

constant

12. How do you write an IF statement in JavaScript?

if (condition) { // code }

if condition: // code

if { // code } condition

condition ? // code : // code

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

break

exit

return

end

14. Which method is used to remove the last element from an array in JavaScript?

removeLast()

pop()

deleteLast()

splice()

15. What is the purpose of the 'addEventListener' method in JavaScript?

To remove an event listener

To add a new element to the DOM

To handle user input

To attach an event handler to an element

16. What is the purpose of 'localStorage' in JavaScript?

Stores data with no expiration date

Stores data with a short expiration date

Stores session-specific data

Stores data in cookies

17. How do you define a JavaScript class?

class MyClass {}

function MyClass() {}

var MyClass = {};

new Class('MyClass')

18. 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

19. What is the purpose of 'JSON.stringify()' in JavaScript?

Converts an object to a JSON string

Parses a JSON string

Creates a new JSON object

Deletes a JSON property

20. What does the 'NaN' in JavaScript stand for?

Not a Number

No Available Number

Negative Available Number

Null and Negative

21. What is the purpose of the 'addEventListener()' method in JavaScript?

Attaches an event handler to an element

Adds a new CSS class

Removes an element from the DOM

Creates a new HTML element

22. What is the purpose of the 'map' function in JavaScript?

To create a new array with the results of calling a provided function on every element in the array

To filter elements in an array

To reduce the array to a single value

To reverse the elements of an array

23. 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

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

parseJSON

evalJSON

JSON.parse

parseString

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

'22'

'4'

An error

26. 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

27. What does HTML stand for?

Hyper Text Markup Language

Hyperlinks and Text Markup Language

Home Tool Markup Language

Hyper Transfer Markup Language

28. Which operator is used for strict equality in JavaScript?

===

!==

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

element.hasClass()

element.isClass()

element.containsClass()

element.classList.contains()

30. Which of the following is a falsy value in JavaScript?

NaN

false

All of the above

JavaScript MCQ Test 3