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Table of contents
1.
Introduction
2.
Front End Developer Interview Questions for Freshers
2.1.
1.What do you mean by a front-end developer?
2.2.
2. What inspiration pushed you to become a front-end developer?
2.3.
3. What are meta tags in HTML?
2.4.
4. State some basic design element.
2.5.
5. What is load balancing?
2.6.
6. What npm stands for?
2.7.
7. What is scope in JavaScript?
2.8.
8. How are JavaScript and jQuery different?
2.9.
9. What is  Content Security Policy?
2.10.
10. What is Cross-Site Scripting(XSS)?
2.11.
11. What skills do you need to become a front-end developer?
2.12.
12. What do you mean by a box model in CSS?
2.13.
13. What is the process for creating a responsive website?
2.14.
14. What do you understand by meta tags in HTML?
2.15.
15. What do you mean by scope in JavaScript?
2.16.
16. What do you mean by RESTful web services?
2.17.
17. What do you understand by an event in JavaScript?
2.18.
18. Why do we need media queries in CSS?
3.
Intermediate Level Front End Developer Interview Questions
3.1.
19. How will you approach debugging a cross-browser compatibility issue?
3.2.
20. Explain the differences between HTML and XHTML.
3.3.
21. Explain the difference between responsive and adaptive design.
3.4.
22. As a front-end developer, how can you optimize a website for performance?
3.5.
23. How JavaScript and jQuery are different from each other?
3.6.
24. Why do we need sass as a front-end developer?
3.7.
25. What is React JS, and why is it used?
3.8.
26. What is Node.js, and why is it used?
3.9.
27. What do you mean by retina graphics, and how to handle them?
3.10.
28. How CSS3 is different from CSS2?
4.
Front End Developer Interview Questions for Experienced
4.1.
29. How to optimize a website's accessibility and SEO?
4.2.
30. What do you understand by version control tools like Git as a front-end developer?
4.3.
31. How to build or integrate an API with front-end applications?
4.4.
32. Explain hoisting in JavaScript.
4.5.
33. Explain the differences between == and === in JavaScript.
4.6.
34. What do you mean by cookies in JavaScript?
4.7.
35. What is Bootstrap, and what are its benefits?
4.8.
36. What do you understand by closure in JavaScript?
4.9.
37. How MongoDB and MySQL are different from each other?
4.10.
38. What do you mean by the SOLID principle in front-end development?
5.
Frequently Asked Questions
5.1.
What to expect in a front-end interview?
5.2.
Why do you want to be a front-end developer interview answer?
5.3.
How do I prepare for a front-end technical interview?
6.
Conclusion
Last Updated: Mar 27, 2024
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Top Frontend Developer Interview Questions and Answers

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Introduction

A front-end developer is a developer who has specialization in building user interfaces for websites and web applications. They work with HTML, CSS, and JavaScript. They create the visual and interactive elements of a web application that users can interact with. The goal of a front-end developer is to ensure that the user's experience is seamless and intuitive. They ensure the interface is visually appealing and easy to use. They work closely with designers, back-end developers, and other stakeholders. They ensure that the final product meets both technical and business requirements.

front end developer interview questions

In this article, we will discuss top frontend developer interview questions and answers. Let us start with the beginner-level top frontend developer interview questions. 

Front End Developer Interview Questions for Freshers

1.What do you mean by a front-end developer?

Front-end developers are those who specialize in building the client-side or user-facing parts of websites and web applications. They use technologies such as HTML, CSS, and JavaScript to create visuals. They create interactive elements of a web application that users can interact with. 

2. What inspiration pushed you to become a front-end developer?

I am always passionate about design and technology. I have a creative mind and a logical mind for problem-solving. I think that front-end development is the perfect combination of both. I love to bring design concepts to life. I create interactive, visually appealing interfaces that enhance the user experience. The endless possibilities constantly inspire me in the field. I am excited to continue learning and growing as a front-end developer.

3. What are meta tags in HTML?

  • Meta tags in HTML are used for the definition metadata of an HTML document. The information about the data is known as metadata.
     
  • Syntax of a metatag is : <meta name= “attributeName” content=”attributeValue”’>
     
  • The <meta> tag is placed under the <head> tag.
     
  • Meta tags are used in search engine optimization, defining viewport, giving page descriptions, etc.
     
  • Search engines, browsers, and web services use them to scan a site or webpage.
     
  • Example: <meta charset=”UTF-8”>

4. State some basic design element.

  • Front-end is a combination of graphic design and user interface. Both of them are created with utmost responsibility. While the User interface requires more technical work by using HTML, CSS, and javascript.
     
  • Layout is the arrangement of content on a webpage that plays a major role in the overall look of a website.
     
  • The selection of appropriate fonts, sizes, and color themes for a website enhances the overall look and feel of the website. 

5. What is load balancing?

Load balancing refers to the distribution of network traffic equally among the pool of resources that support an application, or it can also be referred to as the distribution of incoming network traffic among the group of backend services called server pool or server farm. Applications usually have many resources served with duplicate data for handling high volumes of traffic. 

6. What npm stands for?

npm stands for Node package manager. It is a free package manager for Node.js where all npm packages are defined in files known as package.json.  npm consists of command-line tools that help install different packages and manage their dependencies.

7. What is scope in JavaScript?

Scope in Javascript refers to the accessibility of variables, functions, and objects from various parts of the code. In javascript, a variable has two types of scope, global and local scope. Global scope refers to the declaration outside a function or at the top of the program, while the local scope is when a variable can be accessed only within a function.

8. How are JavaScript and jQuery different?

Javascript is a programming language. On the other hand, jQuery is a library that contains JavaScript code. jQuery can also be referred to as a ‘write less, do more’ Javascript library as it makes Javascript easy to use on our website.

For example,

Javascript: document.getElementById(‘element’).style.fontSixe=’25px’;
jQuery:  $(‘#element’).style.fontSize=’25px’;

9. What is  Content Security Policy?

Content Security Police are used for enhancing the security of the webpage. It is the name of an HTTP response header that provides an additional layer of protection from clickjacking, cross-site scripting (XSS), and other code injection attacks. This security standard can be referred to as a defensive measure against attacks whose intent is to execute malicious content in a web context.

10. What is Cross-Site Scripting(XSS)?

When an attacker injects malicious executable scripts into an application’s or website’s code, it is referred to as Cross-Site Scripting (XSS). Usually, attacks initiate it by sending a malicious link to a user and tempting them to click it. Cross-site scripting works by manipulating a vulnerable web application, which in turn returns s malicious Javascript to users. After the execution of the code in the user's browser, an attacker can comprise their interaction with the particular application.

11. What skills do you need to become a front-end developer?

Here are some primary skills that are essential for becoming a front-end developer:

  • HTML and CSS
     
  • JavaScript
     
  • Responsive design
     
  • Cross-browser compatibility
     
  • Debugging Skills
     
  • Version control
     
  • Interpersonal skills
     
  • Adaptability
     
  • Problem-solving skills
     
  • Attention to detail

12. What do you mean by a box model in CSS?

The box model in CSS refers to the width and height of an HTML element that is calculated, including any padding, borders, and margins.

Every HTML element is considered a rectangular box and each box has four parts:

  • Content
     
  • Padding
     
  • Border
     
  • Margin

13. What is the process for creating a responsive website?

Here is a process for creating a responsive website:

  • Understanding the requirements
     
  • Planning and prototyping
     
  • Setting up the development environment
     
  • Building the basic structure
     
  • Implementing responsive design
     
  • Adding interactivity
     
  • Testing
     
  • Deployment
     
  • Maintenance

14. What do you understand by meta tags in HTML?

Meta tags are those HTML elements that provide metadata or information about the data of a web page. These meta tags are used to provide information to search engines and web browsers about a web page’s content. These are placed in the head section of an HTML document. They provide information such as the page's description, keywords, author, and other metadata.

15. What do you mean by scope in JavaScript?

In JavaScript, the scope means accessibility and visibility of variables and functions within a particular block of code. The scope checks where a variable or function can be accessed within a program.

There are two types of scopes available in JavaScript:

  1. Local scope
     
  2. Global scope

16. What do you mean by RESTful web services?

REST stands for REpresentational State Transfer. It is a software architectural style for creating web services. REST is based on HTTP (Hypertext Transfer Protocol). HTTP is used for transmitting data over the internet. RESTful web services are a way of providing information and services over the internet using standard HTTP methods including GET, POST, PUT, and DELETE.

17. What do you understand by an event in JavaScript?

An event in JavaScript refers to an action or occurrence. If a user clicks on a button, a page finishes loading, or an element is updated, that takes place in the browser and can be handled by JavaScript code. 

Some common events in JavaScript include:

  • dblclick,
     
  • mouseover,
     
  • mouseout,
     
  • submit,
     
  • change, etc.

18. Why do we need media queries in CSS?

Media queries are used in CSS(Cascading Style Sheet) to create responsive designs. A web page can adapt to different screen sizes and device types using media queries. They allow you to apply different styles to a web page based on the dimensions of the viewport, such as the width and height of the screen.

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Intermediate Level Front End Developer Interview Questions

19. How will you approach debugging a cross-browser compatibility issue?

Debugging cross-browser compatibility issues can be a challenging task, but there are several steps you can take to effectively resolve these issues. 

Here is a general process that can help:

  • Identify the problem(use tools such as browser dev tools)
     
  • Reproduce the issue
     
  • Check for known compatibility issues
     
  • Check for vendor prefixes(such as animations and transitions)
     
  • Use a CSS Reset(such as normalize.css)
     
  • Use a cross-browser testing tool(BrowserStack or Sauce Labs)
     
  • Write cross-browser compatible code
     
  • Testing again on different browsers and devices.
     

By following these steps, you can effectively resolve cross-browser compatibility issues and ensure that your website looks and works great in all browsers.

20. Explain the differences between HTML and XHTML.

HTML (Hypertext Markup Language) and XHTML (Extensible Hypertext Markup Language) are both markup languages used to create web pages. 

However, there are some primary differences between the two, which are mentioned below:

HTML XHTML
HTML has a relatively loose syntax. It can allow for errors such as unclosed tags or unquoted attribute values. XHTML has a stricter syntax that requires all tags to be properly closed. All attribute values are to be enclosed in quotes.
HTML is forgiving and can tolerate errors and mistakes. This makes it easier to create web pages, but it can also lead to inconsistent rendering across different web browsers.  XHTML is more strict and requires that pages be well-formed. This makes it more consistent across different browsers.
HTML is served with the MIME type "text/html,". XHTML is served with "application/xhtml+xml."
HTML does not have a formal namespace. XHTML has a formal namespace. This allows for more extensibility and modularity.
HTML is less extensible than XHTML. XHTML is more extensible than HTML. It allows developers to create their own custom tags and attributes.

21. Explain the difference between responsive and adaptive design.

Responsive design is an approach to web design. In responsive design, the content and layout of a website are adjusted and optimized to fit various screen sizes and devices. The design responds to the size of the device by changing the layout and content accordingly.

On the other hand, adaptive design means creating multiple website versions. Each website is optimized for a specific screen size or device. When a user visits the website, the server detects the device being used. And it serves the version of the website that is best suited for that device.

22. As a front-end developer, how can you optimize a website for performance?

As a front-end, it is necessary to optimize a website for performance. It involves reducing its load time, improving its loading speed, and ensuring a good user experience for visitors. Some techniques that you can follow to optimize a website for performance:

  • Minimize HTTP requests
     
  • Image optimization
     
  • Minify HTML, CSS, and JavaScript
     
  • Use a Content Delivery Network (CDN)
     
  • Enable browser caching
     
  • Minimize the use of plugins
     
  • Use lazy loading for videos and heavy content
     
  • Optimize your database
     
  • Reduce redirects
     
  • Use a fast and reliable hosting provider

23. How JavaScript and jQuery are different from each other?

JavaScript and jQuery are related but different.

JavaScript is a programming language. It is used to create dynamic, interactive websites and web applications. It is a core web technology and is supported by all modern web browsers.

On the other hand, jQuery is a popular JavaScript library. It simplifies the process of working with the Document Object Model (DOM). It provides a wide range of pre-built functions and features. It makes it easier to write complex JavaScript programs. It enables developers to achieve more with less code.

24. Why do we need sass as a front-end developer?

Sass (Syntactically Awesome Style Sheets) is a preprocessor scripting language. It is interpreted or compiled into Cascading Style Sheets (CSS). It adds extra functionality to CSS. It makes it easier to write and manage large and complex stylesheets.

As a front-end developer, you may need Sass (Syntactically Awesome Style Sheets) for the following reasons:

  • Improved Productivity
     
  • Modular code
     
  • Better Organization
     
  • Compatibility
     
  • Large community and resources

25. What is React JS, and why is it used?

React JS is an open-source JavaScript library. It is used for building user interfaces or UI components. It allows you to create reusable UI components that we can combine to build complex UIs. React JS works by creating a virtual representation of the UI in memory, which is called the virtual DOM (Document Object Model). 

React JS is used for the following reasons:

  • Component-based architecture
     
  • Declarative approach
     
  • Uses Virtual DOM
     
  • Large community and ecosystem
     
  • Cross-platform development

26. What is Node.js, and why is it used?

Node.js is an open-source, cross-platform JavaScript runtime environment. It executes JavaScript code outside of a web browser. It is built on Chrome's V8 JavaScript engine. It allows developers to create server-side web applications using JavaScript. Node.js is used for various tasks, which are mentioned below:

  • To create server-side web applications(such as APIs (Application Programming Interfaces))
     
  • To create networking applications(such as chat applications and online games)
     
  • To create real-time web applications(such as online collaboration tools and live-updating dashboards)
     
  • To create command-line tools(such as package managers and task runners)
     
  • To create microservices

27. What do you mean by retina graphics, and how to handle them?

Retina graphics refer to high-resolution graphics. These are designed to look sharp on devices with high pixel densities, such as smartphones and tablet devices. To handle retina graphics in web development, there are a few techniques that you can use:

  • Use vector graphics(such as SVG)
     
  • Use high-resolution images
     
  • Use CSS3 techniques
     
  • Use a responsive design
     

By using these strategies, you can ensure that your graphics look fantastic on all devices, including those with high pixel densities.

28. How CSS3 is different from CSS2?

The latest version of the Cascading Style Sheets (CSS) language is CSS3. It brings several improvements and new features compared to CSS2. 

Some of the features present in CSS3 but not in CSS2:

  • Modularization.
     
  • New selectors(such as nth-child(), :first-of-type(), and :last-of-type())
     
  • Backgrounds and borders
     
  • New text effects
     
  • Animations
     
  • Media Queries
     
  • Flexbox Layout

Front End Developer Interview Questions for Experienced

29. How to optimize a website's accessibility and SEO?

We can optimize a website’s accessibility using the following ways:

  • Use proper HTML structure and semantics. It makes the website easy to understand for both users and assistive technologies.
     
  • Use descriptive and concise text for links, images, and other web page elements.
     
  • Provide alternative text(alt text) descriptions for images and other non-text content.
     
  • Use good color contrast to make content easily visible.
     
  • Make sure the website is keyboard navigable.
     

We can optimize a website’s SEO(Search Engine Optimization) in the following ways:

  • Use proper HTML structure and semantics. It makes the website easy to understand for search engines.
     
  • Include descriptive and concise meta titles and descriptions for each web page.
     
  • Use relevant and descriptive headings to break up content.
     
  • Make sure that the website is mobile-friendly and it loads quickly.
     
  • Use relevant keywords in page content, but avoid keyword stuffing.
     
  • Include internal and external links to relevant content.
     
  • Use alt tags and proper file names for images.

30. What do you understand by version control tools like Git as a front-end developer?

As a front-end developer, version control tools like Git help to manage changes. It provides features for collaboration with others in a project. Git allows developers to keep track of changes made to code over time. We can revert to previous versions of code and collaborate with others on the same codebase.

Some common use cases for version control with Git in front-end development are mentioned below:

  • Keeping track of changes to HTML, CSS, and JavaScript files.
     
  • Collaborating with other developers on a codebase.
     
  • Branching and merging code changes for different features or experiments in a project.
     
  • Creating backups of code.
     
  • Identifying who made changes to the code and when.
     
  • Roll back to a previous version of the code if necessary.
     
  • Managing code releases and deployments.

31. How to build or integrate an API with front-end applications?

To build or integrate an API with front-end applications, you can follow these steps:

  1. Determine the purpose and requirements of the API that you want to build or integrate.
     
  2. Choose an appropriate API technology, such as REST or GraphQL.
     
  3. Design the API, which has endpoints, data structures, and expected responses.
     
  4. Implement the API using a server-side programming language, such as Node.js, Python, or Ruby.
     
  5. Test the API using tools like Postman.
     
  6. Make secure API by implementing authentication and authorization mechanisms.
     
  7. Document the API, including usage instructions and examples of responses.
     
  8. Integrate the API with your front-end application by requesting API endpoints using technologies like JavaScript or AJAX(Asynchronous JavaScript And XML).
     
  9. Handle API responses, including error handling and data parsing.
     
  10. Test the integration and check whether the data transfers properly between the API and the front-end application.

32. Explain hoisting in JavaScript.

Hoisting is a behavior in JavaScript in which the variables and function declarations are moved to the top of their respective scopes(global or local) during the compilation phase before any code is executed.

The variable and function can be used before they are declared as long as they are declared in the same scope. For example

// Output: undefined
console.log(val);
var val = 25;


In the above code, we have declared a variable val and assigned a value of 25 after it has been referenced in the console.log statement. However, since the declaration is hoisted to the top of the scope, the output of console.log(val) will be undefined.

Similarly, function declarations are also hoisted to the top of their respective scopes. For example,

// Output: "Hello, Ninjas!"
ninjas(); 
function ninjas() {
  console.log("Hello, Ninjas!");
}


In the above code, the ninjas function is declared and defined after it has been called. Since the function declaration is hoisted to the top of the scope, the output of ninjas() will be "Hello, Ninjas!".

It's important to remember that only the declarations are hoisted, not the assignments. So, in the case of variables declared with let and const, they will not be accessible until they are assigned a value.

33. Explain the differences between == and === in JavaScript.

In JavaScript, both == and === are used for comparison, but they have different behaviors. Here are some of the differences between them.

== ===
It is a loose equality operator, which means it will perform type conversion if the operands have different types. It is also known as the strict equality operator, which means it does not perform type conversion.
It only returns true if the operands have the same value. It will not check their types. It only returns true if the operands are of the same type and have the same value.
It is slower than === because it needs to perform type conversion. It is faster than == because it does not need to perform type conversion.
It is not much safer than ===. It is safer than ==.

34. What do you mean by cookies in JavaScript?

In JavaScript, cookies are small text files. These are stored on a user's computer by a website. They are used to store user-specific information, such as login credentials, shopping cart items, and preferences.

Cookies are created and accessed using the document.cookie property. Here's an example of setting a cookie with JavaScript:

document.cookie = "username=Coding ninjas; 
expires=Sat, 18 Feb 2023 23:59:59 GMT";


In the above code, a cookie named username is created with the value of Coding ninjas and an expiration date of February 18, 2023.

It's important to remember that cookies can be a potential security risk if they contain sensitive information. For this reason, it's recommended to use cookies only for non-sensitive data. We should use proper security measures, such as encryption and HTTP-only cookies, for sensitive data.

35. What is Bootstrap, and what are its benefits?

In front-end web development, "Bootstrap" is a popular open-source CSS framework. It provides pre-designed HTML, CSS, and JavaScript components for building responsive and mobile-first web applications. The benefits of using Bootstrap are mentioned below:

  • Saves time and effort by providing ready-to-use UI(User Interface) components and design templates.
     
  • It helps to ensure cross-browser compatibility. It provides responsiveness to web pages on different devices.
     
  • It provides a consistent and visually appealing design for web applications.
     
  • It offers customizable and extensible components which are used in advanced front-end development.
     
  • It has a large community of developers and resources that are available for support and learning.

36. What do you understand by closure in JavaScript?

In JavaScript, closure combines a function and the lexical environment. The lexical environment consists of any local variables that were in scope when the closure was created.

Closures are created whenever a function is defined inside another function. The inner function references a variable from the outer function's scope. Here's an example:

function outerFun() {
  const val = 20;
  function innerFun() {
    console.log(val);
  }
  return innerFun;
}
const innerVal = outerFun();
console.log("Returned value is");
innerVal(); 


We will see the output as follows:

Returned value is
20


In the above code, the innerFun function is defined inside the outerFun function. innerFun() references the val variable from the outerFun function's scope. When the outer function is called, it returns the innerFun function, which is then assigned to the innerFunc variable. When innerVal is called, it still has access to the val variable, even though the outerFun function has already been completed.

37. How MongoDB and MySQL are different from each other?

The difference between MongoDB and MySQL is mentioned in the table below.

MongoDB MySQL
It is an open-source database which is developed by MongoDB, Inc. It stores data in JSON(JavaScript Object Notation) format that can vary in structure. It is a NoSQL database. It is an open-source relational database management system (RDBMS). It is developed, distributed, and supported by Oracle Corporation.
Each individual record is stored as a document. Each individual record is stored as a row in a table.
Documents belonging to a particular class or group are stored in a collection. A table stores rows (records) of a similar type.
It was designed with high availability and scalability. It includes an out-of-the-box replication and sharding. It does not allow efficient replication and sharding. With MySQL, we can access associated data using joins which helps to minimize duplication.

38. What do you mean by the SOLID principle in front-end development?

The SOLID principle is a set of five design principles in object-oriented programming. It can be applied to front-end development to improve the quality, maintainability, and scalability of code. The five principles are as follows:

  1. Single Responsibility Principle (SRP): A component or module should have only one reason to change.
     
  2. Open-Closed Principle (OCP): A component or module should be open for extension but closed for modification.
     
  3. Liskov Substitution Principle (LSP): Subtypes should be substitutable for their base types.
     
  4. Interface Segregation Principle (ISP): Clients should not be forced to depend on methods they do not use.
     
  5. Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules. Both should depend on abstractions.
     

By following these principles, developers can create more modular, flexible, and testable code. That code can be easier to maintain and extend over time.

Also Read About, javascript replace

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Frequently Asked Questions

What to expect in a front-end interview?

In a front-end interview, one should be prepared with the knowledge about the tech stack being used, such as HTML, CSS, and JavaScript. One should know about the concepts and be prepared to discuss all the components with various tools, frameworks, and programming languages.

Why do you want to be a front-end developer interview answer?

The answer can include all the points which excite you about being a front-end developer. Here is a sample answer, “I have always been passionate about web development as I am motivated by the new innovations in web technologies which makes me passionate about creating visually appealing and interactive applications.”

How do I prepare for a front-end technical interview?

To prepare for a front-end technical interview, firstly, one should be well-versed which the fundamental concepts of HTML, CSS, and Javascript. In the front-end knowledge part, you must explain your projects in depth and be prepared for recreating a design that an interviewer may ask. 

Conclusion

In this article, we have discussed top frontend developer interview questions and answers. We have discussed interview questions in three categories: beginner, intermediate, and advanced. You can check out our other interview questions blogs:

We hope this article helped you in learning about front-end developer interview questions. You can read more such articles on our platform, Coding Ninjas Studio. You will find articles on almost every topic on our platform. Also, you can practice coding questions at Coding Ninjas to crack good product-based companies. For interview preparations, you can read the Interview Experiences of popular companies

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