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

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

pop()

push()

shift()

unshift()

2. How do you handle errors in asynchronous JavaScript code?

Using try...catch

Using if...else

Using switch statement

Using for loop

3. 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

4. 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

5. 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

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

removeLast()

pop()

deleteLast()

splice()

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

if (condition) { // code }

if condition: // code

if { // code } condition

condition ? // code : // code

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

Handles asynchronous operations

Performs mathematical calculations

Creates an array of elements

Defines a function

9. How do you comment in JavaScript?

// This is a comment

# This is a comment

/* This is a comment */

10. 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

11. How do you create an object in JavaScript?

let obj = {}

new Object()

Object.create()

All of the above

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

join()

concat()

merge()

combine()

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

concat

14. How do you declare a variable in JavaScript?

let

var

const

all of the above

15. 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

16. 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

17. How do you declare a function in JavaScript?

function myFunction() { // code }

def myFunction():

create function myFunction():

new_function myFunction():

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

===

!==

19. 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

20. 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

21. How do you declare a variable in JavaScript?

v myVar;

var myVar;

variable myVar;

let myVar;

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

innerHTML

textContent

innerText

appendText

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

Prints output to the console

Defines a new variable

Creates a loop

Imports a module

24. 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

25. How do you declare a function in JavaScript?

function: myFunction()

func myFunction()

function myFunction()

def myFunction()

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

push()

pop()

shift()

unshift()

27. 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

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

'22'

'4'

An error

29. 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

30. 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

JavaScript MCQ Test 3