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

1. What is the purpose of the 'fetch' function in JavaScript?

To retrieve data from a server

To delete data from a server

To update data on a server

To send an email

2. How do you define a JavaScript class?

class MyClass {}

function MyClass() {}

var MyClass = {};

new Class('MyClass')

3. 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

4. What is the result of the expression '3 * '2' + 1' in JavaScript?

Error

Undefined

5. How do you comment a single line in JavaScript?

// This is a comment

/* This is a comment */

# This is a comment

' This is a comment

6. What does HTML stand for?

Hyper Text Markup Language

Hyperlinks and Text Markup Language

Home Tool Markup Language

Hyper Transfer Markup Language

7. 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

8. How do you create a class in JavaScript?

class MyClass {}

function MyClass() {}

create class MyClass {}

new Class MyClass {}

9. How do you round the number 7.25 to the nearest integer in JavaScript?

Math.round(7.25)

Math.ceil(7.25)

Math.floor(7.25)

round(7.25)

10. What does CSS stand for?

Counter Style Sheet

Computer Style Sheet

Colorful Style Sheet

Cascading Style Sheet

11. Which method is used to add an element to the end of an array in JavaScript?

push()

pop()

shift()

unshift()

12. What is the purpose of 'Array.prototype.reduce()' in JavaScript?

Reduces an array to a single value

Reverses the elements of an array

Creates a new array with elements passing a test

Sorts the elements of an array

13. What is the purpose of 'Array.isArray()' in JavaScript?

Checks if a variable is an array

Adds an element to an array

Removes an element from an array

Sorts the elements of an array

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 of the following is a benefit of using JavaScript modules?

Encapsulation

Code Reusability

Dependency Management

All of the above

16. What is the purpose of 'Array.prototype.map()' in JavaScript?

Applies a function to each element of an array

Adds a new element to an array

Filters elements of an array

Reverses the elements of an array

17. Which method is used to convert a string to uppercase in JavaScript?

toUpperCase()

toUpper()

toUpperCaseCase()

upperCase()

18. How do you write a multi-line comment in JavaScript?

/* This is a multi-line comment */

// This is a multi-line comment

# This is a multi-line comment

' This is a multi-line comment

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

break

exit

return

end

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

===

!==

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

if (condition) { // code }

if condition: // code

if { // code } condition

condition ? // code : // code

22. 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

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

var myArray = []

array myArray = []

new Array()

myArray = {}

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

Prints output to the console

Defines a new variable

Creates a loop

Imports a module

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

undefined

26. How do you declare a variable in JavaScript?

v myVar;

var myVar;

variable myVar;

let myVar;

27. 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

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

pop()

push()

shift()

unshift()

29. 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

30. What is the purpose of the 'reduce' method 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

31. How do you create a comment in JavaScript?

// This is a comment

# This is a comment

/* This is a comment */

32. 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

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

element.addClass()

element.classList.add()

element.addClassList()

element.addStyle()

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

NaN

false

All of the above

35. What is the purpose of the 'setTimeout' function in JavaScript?

To delay the execution of a function

To set a timer

To repeat a function at regular intervals

To execute a function immediately

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

element.hasClass()

element.isClass()

element.containsClass()

element.classList.contains()

37. Which operator is used to concatenate strings in JavaScript?

concat

38. How do you create an object in JavaScript?

let obj = {}

new Object()

Object.create()

All of the above

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

removeLast()

pop()

deleteLast()

splice()

40. How do you comment in JavaScript?

// This is a comment

# This is a comment

/* This is a comment */

41. What is a closure in JavaScript?

A way to create private variables

A function that has access to variables in its lexical scope

An object with no properties

A special type of loop

42. What is the purpose of 'Array.prototype.filter()' in JavaScript?

Creates a new array with elements passing a test

Removes elements from an array

Sorts the elements of an array

Reverses the elements of an array

43. 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

44. 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

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

join()

concat()

merge()

combine()

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

parseJSON

evalJSON

JSON.parse

parseString

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

'22'

'4'

An error

48. How do you declare a variable in JavaScript?

let

var

const

all of the above

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

Handles asynchronous operations

Performs mathematical calculations

Creates an array of elements

Defines a function

50. 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

JavaScript MCQ Test 1