Top 20 JavaScript MCQs for Front-End Developers to Ace Your Interview!

Last updated by Rishabh Dev Choudhary on Dec 22, 2024 at 09:08 PM

| Reading Time: 3 minutes

With tech giants like Uber, Netflix, Google, Microsoft, and many more leveraging the power of JavaScript, front-end developers are expected to be well-versed in the language. JavaScript MCQs for front-end developers are a must-know for tech aspirants aiming for this role.

JavaScript is the most used programming language, with 63.61% of the developers using it worldwide. There are innumerable opportunities available for developers with JavaScript basics and advanced understanding, but still, extensive effort is required to grab a job as a front-end developer. A strong understanding of the fundamentals, JavaScript basics, and ES6 MCQs is a commonly recommended expert tip.

Aiding you in the process of landing your dream job at the top-tech company, developing confidence, going through MCQs, and revision is helpful. Thus, here we bring you a collection of the most asked JavaScript MCQs for front-end developers and JS interview questions.

Understanding JavaScript

JavaScript is a scripting language used in combination with CSS and HTML to create dynamic web pages. Also referred to as the building block of web development, it is used to develop mobile applications, too. The syntax of JavaScript is based on Java and C languages. Here are certain key features of JavaScript.

Dynamic typing
Platform independence
Lightweight
Control statements
Line-by-line execution
Easy interpretation by a web browser
Functional style
Prototype-based
Case sensitive
Event handling

Understanding ES6

ECMAScript or ES is the standardized specification for scripting languages like JavaScript. JavaScript is an implementation of the ECMAScript specification. ES6, or ECMAScript 6, was the sixth version of the ECMAScript standard released in 2015. It provided certain key contributions to JavaScript, which include:

Arrow functions
let and const declarations
Object entries
Object and array destructuring
Template literal
String and array methods
for/of loop and others

20 JavaScript MCQs for Front-End Developers

Strengthen your JavaScript basics with JS interview questions and ES6 MCQs:

Q1. State the Characteristics of Negative Infinity.

It is a constant
It is variable
It stated no other number is greater than this value
Both a and c

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜aâ€™ – It is a constant

Q2. State the Keyword Used to Declare Block-Scoped Variables in ES6.

â€˜blockâ€™
â€˜varâ€™
â€˜letâ€™
â€˜constâ€™

Answer: c. â€˜letâ€™

Q3. What will be the Output of the Following JavaScript Code?

Error
6
2
10

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜câ€™ – 2

Q4. Which of These is Used to Declare a Constant Data Type?

constant
cons
const
cnst

Answer: c. const

Q5. Which of These is a Class in ES6?

Function
Basic data type
Variable
Derived datatype

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜aâ€™ – Function

Q6. What is the Role of the JavaScript Engine?

Compilation
Interpretation
Parsing
Compilation and parsing

Answer: b. Interpretation

Q7. What will be the Output of the Given Code?

Undefined
20
Error
40

Answer: d. 40

Q8. Choose the Correct JavaScript Syntax that can be Used to Modify the Following Statement:

<p id=”demo>Welcome to JavaScript Quiz</p>

Document.get ElementByName(â€œpâ€).innerHTML = â€Hello Candidates!â€;
demo.innerHTML= â€Hello Candidates!â€;
document.getElement(â€œpâ€).innerHTML = â€Hello Candidates!â€;
document.getElementByID(â€œdemoâ€).innerHTML = â€Hello Candidates!â€;

Answer: d. document.getElementByID(â€œdemoâ€).innerHTML = â€Hello Candidates!â€;

Q9. Where Should You Insert JavaScript Code in an HTML Document?

The <head>section
The <body> section
Both <head> and <body> section
Anywhere in the HTML file

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜câ€™ – Both and section

Q10. What is the x = = = y Statement Interpreted as in JavaScript?

State that x and y have equal value
State that x and y are not equal
State that x and y are equal in type, value, and reference address
State that x and y are equal in value and reference address only

Answer: c. State that x and y are equal in type, value, and reference address

Q11. What is the Purpose of the â€˜Symbolâ€™ Data Type Introduced in ES6?

To represent immutable data
To define asynchronous operations
To create unique identifiers
To create generator functions

Answer: c. To create unique identifiers

Q12. Which Among These is the Correct Combination for Loop on a Loop Variable?

Initialization, updation, and incrementation
Initialization, testing, and updation
Initialization, incrementation, and testing
Initialization, updation, and initialization

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜bâ€™ – Initialization, testing, and updation

Q13. How can you Determine the Status of a CheckBox Element with the id “IK” in JavaScript?

document.getElementById(“IK”).isChecked;
document.getElementById(“IK”).isSelected;
document.getElementById(“IK”).checked;
document.getElementById(“IK”).value;

Answer: c. document.getElementById(“IK”).checked;

Q14. What is the Primary Difference Between JavaScript and JScript?

JavaScript is a client-side scripting language, whereas JScript is a server-side scripting language
JavaScript is developed by Mozilla, whereas JScript is developed by Microsoft
JavaScript is an open-standard scripting language, whereas JScript is a Microsoft implementation of JavaScript.
JavaScript is used for creating web applications, whereas JScript is used for creating desktop applications.

Answer: c. JavaScript is an open-standard scripting language, whereas JScript is a Microsoft implementation of JavaScript

Q15. Give the Output for the Following Code:

15
78
Runtime error
Compilation error

Answer: b. 78

Q16. Which is the Use of the Array â€œmap()â€ Method?

It only passes the data item of one array to other arrays
It passes the data item of the array and also returns the essential mapped elements
It applies a particular function to each element of the array it is called on and generates a new array containing the results of the function calls
It only maps the elements of other arrays

Answer: c. It applies a particular function to each element of the array it is called on and generates a new array containing the results of the function calls

Q17. Which Function Does Not Return a Value?

Dynamic function
Method
Static function
Processes

Answer: d. Processes

Q18. Which Function is Used to Eliminate the Last Element From the Array?

pop()
deleteLast()
splice()
removeLast()

Answer: a. pop()

Q19. What is the Role of Object-Oriented Programming in JavaScript?

Code organization into classes and objects
Elimination of the function needs
Faster code execution
Shorten the code length

Answer: a. Code organization into classes and objects

Q20. Which is Used to Calculate String Variables in JavaScript?

let
const
var
All of the above

Answer: The right answer to this JavaScript MCQ for front-end developers is â€˜dâ€™ – All of the above

Become a Pro in JavaScript with Interview Kickstart

As JavaScript continues to remain the preferred programming language for developers, questions based on it are common during the interview. To clear the interview, you should know the JavaScript MCQs for front-end developers is important.

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FAQs: JavaScript MCQs for Front-End Developers

Q1. How do I Turn on My JavaScript?

To activate JavaScript in the browser, open Chrome, head to settings, privacy and security, and select site setting. Now click JavaScript and select the sites that can use JavaScript.

Q2. Who Introduced JavaScript?

Brendan Eich invented JavaScript in 1995.

Q3. Why Won’t My JavaScript Work?

One of the common problems leading to the inability to run JavaScript is corrupted browser cookies or cache.

Q4. Is JavaScript Free and Open Source?

Yes, JavaScript is both free and open source to use.

Q5. Does JavaScript Need a Browser?

JavaScript can run both on web pages and on servers.

Q6. Is JavaScript Used in the Backend?

JavaScript is the common language used for both frontend and backend code.

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