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Top Web Developer Interview Questions and Answers (2024)

Today, we can see almost every person connected to technology, who uses online platforms for their daily tasks. Hence, one of the most significant areas for building and maintaining websites or mobile applications can be done through web development. Today, the need for highly skilled developers is constantly rising as almost all new startups prefer online platforms. Therefore anyone preparing for the web developer interview process, either fresher or any candidate having experience, must have in-depth knowledge of web development along with multiple technologies and best practices.

In this blog, we will see the core concepts and the top web developer interview questions and answers (2024). We will discuss what a web developer focuses on the most and explanation for specific queries asked in the interview. This also includes behavioural questions which are necessary for both freshers and experienced professionals so that one can succeed in their next job interview.

Who is a Web Developer?

The basic role of any web developer is to address website-related queries, which can occur during website building and maintenance. They implement website structure, design, and functionality features using tools and programming languages. Website developers make sure that the sites they create are not only beautiful but also work well on diverse devices/browsers. Web developers bring an artistic vision of designers into the websites we see or the applications we use daily. The code written by any web developer should meet every standard so that the final interface is user-friendly and visually appealing, containing all running interactive elements.

What Are the Roles & Responsibilities of a Web Developer?

Web designers play an essential role in the digital industry, as they have to ensure the operational websites are running without any conflict, preserving all the user-friendly interfaces. Duties may vary depending on several specialisations in web development.

Front-End Development

• Creating User Interfaces (UI): Not all the people using websites or web applications are that friendly with technology, hence users must be able to interact with ease, by designing a user-friendly interface.
• Responsive Design: Building those sites which could adapt well enough, to support various desktops, tablets or mobile phones, all responsive at once.
• Cross-Browser Compatibility: Another important factor is to check if the developed website works correctly on multiple browsers.
• Using HTML, CSS, JavaScript: Writing codes, maintaining page style, and content interactivity, etc.

Back-End Development

• Server-Side Logic: Writing codes, and running server-side logic smoothly without any hitch.
• Database Management: Handle database designing, and processing the data at the backend.
• API Integration: Integrate with other systems’ third-party services and APIs to add functionality like payment gateways or social media features.
• Security Implementation: Adhere to security protocols against hacking and data breaches.

Full-Stack Development

• End-to-End Development: Handle the entire web development process, right from the front-end side to the back-end.
• Troubleshooting and Debugging: Fixing any bugs in a programming code making the site run flawlessly.
• Version Control: Collaborative development of codebase changes can be tracked by using techniques such as Git.

These are just different roles needed for creating & maintaining efficient, safe & user-friendly sites.

Web Developer Interview Questions and Answers For Freshers

1. What is HTML?

HTML (HyperText Markup Language) is the standard language used to create web pages. HTML provides us with some important basic structures which can be used to develop the website. Elements like headings, links, titles, paragraphs, images, etc. can be added to the website using HTML.

2. What is CSS?

CSS (Cascading Style Sheets) is a language used to style and layout web pages. It does this by controlling style-related aspects like the layout as well as variations in the display based on factors such as colours or spacing of the text and other content.

3. What are HTML tags?

HTML tags represent the basics of HTML. They help in defining and ordering web page content. Some examples of HTML tags are text headings, paragraphs, images and hyperlinks.

4. What is the difference between HTML and XHTML?

5. What are CSS Selectors?

CSS selectors are patterns used to select and style specific HTML elements. They allow us to target elements based on their attributes (like class, id, or type) so that we can apply styles across our site without repeating ourselves too much.

6. What is the difference between a block-level and an inline element?

7. What is JavaScript?

A well-known programming language which can add interactivity on web pages, allowing us to create different real-time dynamic content to attract more and more users. It benefits in growing more user-friendly and interesting websites so that people can easily understand, and not get bored of using the same website or mobile application again. JavaScript includes animations, form validation, interactive features, dynamic randomness with time, video playback, caching, etc. enhancing overall user experiences.

8. What is the scope of a variable in JavaScript?

9. What is the use of HTTP cookies?

HTTP cookies are nothing but small chunks of data stored on browsers or any mobile applications, especially when a user interacts with the platform. Hence, cookies may include login credentials, shopping cart contents, website settings (other than default), quick recommendations, etc. Cookies help websites provide a personalised experience for users by remembering their activities and preferences across visits.

10. What are the different ways to include CSS in a webpage?

• Inline CSS: Applied directly to HTML elements using the style attribute.
• Internal CSS: Written within a <style> tag in the <head> section of the HTML document.
• External CSS: Linked as a separate .css file using the <link> tag in the <head> section.

11. Explain the difference between class and id selectors in CSS.

12. What is the DOM?

The DOM (Document Object Model) is a programming interface for web documents. We can say this is a document which represents the structure of any webpage as a tree of objects. Hence, this allows developers to interact and manipulate HTML and CSS. Using the DOM, developers can dynamically change the content, structure, and style of a webpage in response to user interactions or other events.

13. What are JavaScript promises?

JavaScript promises are objects used for asynchronous operations. They represent the eventual completion (or failure) of an operation and its resulting value. Promises have three states: pending, fulfilled, and rejected.

Here’s a simple example of a JavaScript promise:

14. What is the difference between == and === in JavaScript?

15. What specific coding languages do you work with?

• HTML/CSS: For structuring and styling web pages.
• JavaScript: For adding interactivity to web pages.
• Python: For backend development and data processing.
• Java: For building robust, scalable applications.
• SQL: For managing and querying databases.

16. What web development tools do you use?

• VS Code: A powerful code editor with extensions for different languages.
• Git: For version control and collaboration.
• Chrome DevTools: For debugging and optimising web pages.
• npm: For managing packages in JavaScript projects.
• Postman: For testing APIs and server responses.

17. Explain the difference between let, const, and var in JavaScript.

18. How do you organise your JavaScript code?

• Modular Structure: Break down the code into reusable modules or components.
• Consistent Naming Conventions: Use clear and descriptive names for variables and functions.
• Comments and Documentation: Add comments to explain complex code and maintain proper documentation.
• Avoid Global Variables: Keep the global namespace clean by using closures or modules.
• Use Linting Tools: Tools like ESLint help maintain code quality and consistency.

19. How do Inline, Internal, and External CSS differ from each other?

20. What does front-end development entail?

Frontend development has all the development prerequisites to make an interface of any website or mobile application, which can be directly seen by the users. It Includes tasks like designing layouts, templates, responsive designs, and cross-browser compatibility. Front-end developers use languages like HTML, CSS, and JavaScript to build user interfaces and improve user experience.

21. What is the difference between Responsive and Adaptive Design?

22. Define backend in web development.

All the server-side work is done in backend development. Web developers must include logic designing, database implementation, server configurations, and all the other tasks which directly or indirectly connect to the front-end elements. They use languages like Python, Java, and SQL to build the backend infrastructure that powers the front end.

23. What is the purpose of a Doctype in HTML?

A Doctype in HTML is a declaration that informs the web browser about the version of HTML the page is written in. It ensures that the browser renders the page correctly. The Doctype is placed at the very top of an HTML document. Here’s an example:

In modern web development, <!DOCTYPE html> is commonly used to trigger standards mode, ensuring that the browser renders the page according to the latest HTML specifications.

24. How do CSS Preprocessors like SASS and LESS differ?

25. Explain the use of Semantic HTML.

Semantic HTML uses meaningful tags to define the structure and content of a webpage. Tags like <header>, <footer>, <article>, and <section> clearly describe their purpose, improving accessibility and SEO by allowing search engines and screen readers to better understand the content.

26. What are the uses of child selectors in CSS?

Child selectors in CSS are used to style elements that are direct children of a specified parent. They allow for more precise control over styling. Here’s an example:

27. What are the components of the CSS box model?

The CSS box model consists of the following components:

• Content: The actual content of the element, such as text or images.
• Padding: Space between the content and the border, providing inner spacing.
• Border: The line surrounding the padding (if any) and the content.
• Margin: Space outside the border, providing outer spacing that separates elements.

28. What are the various data types present in JavaScript?

29. What are some of the properties of transitions in CSS3?

CSS3 transitions allow for smooth changes between different states of an element. Here are some key properties:

• transition-property: This can specify any CSS property that needs to be transitioned, like some colour or background colour, etc.
• transition-duration: When we define duration, it completes any transition animation in that time interval. For example, 0.5s, etc.
• transition-timing-function: This function controls the overall speed of the transition over time, including speed ramps like ease-in, ease-out linear, etc.
• transition-delay: Delay can help to set multiple transitions and the overall look of the animation.

30. What is the use of pseudo-classes in CSS?

Pseudo-classes in CSS are used to define the special states of an element. They can style elements based on user interaction or position in the document tree. Here’s an example:

31. What is the use of media queries in CSS3?

We can use media queries in CSS3 to apply several styles that are based on the characteristics of any device. This includes screen width, height and overall orientation of the screen of the user’s device, enabling overall responsiveness of the application to adapt to all devices. Here’s an example:

32. What is the difference between Block and Inline Elements in HTML?

33. Why is float used in CSS?

We use the float property to position an element inside a container tag to move left or right, which can allow other content to wrap around it. Hence it has a very common use in creating layouts with images and texts. Here’s an example:

34. What is z-index in CSS?

This feature in CSS is very similar to the layers used in Photoshop or any photo editing application. The z-index controls the order of elements along the z-axis and the stacking helps to either hide other elements underneath top layer elements or to overlay any other element. The higher the z-index value, the more prior it is displayed in front of elements with lower values.

35. What is the difference between <window.onload> and <onDocumentReady>?

36. Why are external style sheets preferred?

External style sheets are preferred because they allow for:

• Consistency: The same CSS file can be applied across multiple pages, ensuring a uniform look.
• Maintainability: Easier to manage and update styles from a single file rather than modifying inline or internal styles in multiple locations.
• Performance: External CSS files are cached by the browser, reducing page load times on subsequent visits.

37. How do JavaScript Libraries (e.g., jQuery) differ from Vanilla JavaScript?

38. What is RESTful API design?

REST stands for Representational State Transfer, which we use to follow the principles while using RESTful APIs. Its design follows all these standards to create web services, using standard HTTP methods like GET, POST, PUT, and DELETE. The CRUD operation (Create, Read, Update, Delete) can be carried out using it. RESTful APIs are stateless, scalable, and designed to work with various data formats, such as JSON and XML.

39. What are WebSockets used for?

Generally, we use WebSockets for real-time bidirectional communication, establishing a connection between a client and a server. It allows us for continuous data exchange over a single, long-lived connection, unlike any other HTTP, that is request-response-base. Therefore it is highly used in live chats, gaming and many applications which use real-time notifications.

40. What are the types of popup boxes present in JavaScript?

41. How are comments used in JavaScript?

Comments in JavaScript are used to explain code, making it easier to understand and maintain.

• Single-line comment: Begins with // and extends to the end of the line.

// This is a single-line comment

let x = 5; // Assign 5 to x

• Multi-line comment: Begins with /* and ends with */.

/* This is a

multi-line comment */

let y = 10;

42. What are undefined and undeclared variables in JavaScript?

43. What are the differences between External and Internal CSS?

Web Developer Interview Questions and Answers For Experienced

44. When you’re looking at other people’s code, how do you test for bugs?

Here, we can say different methods for bug testing like, initially understanding the overall code’s logic and flow, followed by using tools like Chrome DevTools to set breakpoints and steps throughout the code. You must constantly use console.log() statements to keep track of errors and variable values for perfect execution.

45. What is the difference between GET and POST methods in HTTP?

46. How to reduce the loading time of the website?

A more advanced user-experience-related issue is the decrease in websites’ loading time. The following are some of the strategies one can apply:

• Image Optimization: Compress images. Do not compromise on quality but make sure the size goes down.
• Minify CSS, JavaScript and HTML: Squeeze out all the spaces, comments, and characters that are not required to reduce file sizes.
• Lazy Loading: Do not load images and other content until they become necessary.
• Browser Caching: Store some parts of a website on the user’s browser so that there is no need to reload them every time.
• Use a Content Delivery Network (CDN): Serve content from servers closer to the user to reduce load times.

47. How do you vertically and horizontally centre an element using CSS?

Varieties of CSS techniques can be applied in centering an element both vertically and horizontally.

48. How do you style an entire webpage at once?

To style a whole web page at a go, an external CSS stylesheet is generally used. This links the stylesheet to the HTML document. within the <head> section using the <link> tag. In the file styles.css, global styles can be defined to apply to all elements on the page.

49. What is SVG, and why is it used?

SVG (Scalable Vector Graphics) is an XML-based format for creating vector images. We see other raster image formats like PNG or JPEG that are scalable but they might lose overall quality. In SVG, we see they do not lose any quality, irrespective of browsers, devices or size used in the website. Therefore primarily, SVG is used for icons, logos, illustrations and other graphics. SVG’s hard-coded embeddings and properties can be easily read by HTML and do not lose quality on scaling. It also supports interactivity and animation, making it versatile for web use.

50. What are the differences between Static and Dynamic Web Pages?

51. What is the use of Canvas in HTML?

HTML <canvas> elements can draw graphics on any web page through JavaScript. Any web developer using it can create 2D shapes, and images, along with animations. Hence, it is commonly used in creating dynamic graphics like charts, visual effects and game interfaces.

Here’s a basic example:

52. What are the types of CSS?

There are three main types of CSS, each used for different purposes:

• Inline CSS: Applied directly to HTML elements using the style attribute.

<p style=”color: blue;”>This is a blue paragraph.</p>

• Internal CSS: Written within a <style> tag in the <head> section of the HTML document.

<style>

p {

color: blue;

}

</style>

• External CSS: Linked as a separate .css file using the <link> tag in the HTML document.

<link rel=”stylesheet” href=”styles.css”>

53. How do WebSockets differ from HTTP Polling?

54. What is AJAX?

AJAX (Asynchronous JavaScript and XML) is a technique used to create dynamic, interactive web applications. We often use it to update content asynchronously, exchanging all the data with a server in the background. It also does not reload the entire page while in use. AJAX is frequently used for form submissions, loading data, updating parts of a dynamic page, etc. Here’s a simple example:

55. How does a Single-Page Application (SPA) differ from a Multi-Page Application (MPA)?

56. What is lazy loading?

We use lazy loading to defer the loading time of non-critical resources like images, videos or scripts. These resources do not require to be loaded in the very initial phase of website loading, as images and videos can be loaded after some milliseconds from page reload or when the user scrolls down to that resource. Therefore, we see all the important texts, colours, sliders, carousels, navbar, etc. are loaded first, ignoring bigger-sized images or videos which could have taken enough time to load.

57. What are the advantages of HTTP 2.0 over HTTP 1.1?

58. What is pagination, and why is it used?

Pagination is a technique used to divide a large set of data or content into smaller, more manageable chunks or pages. It is commonly used in search results, product listings, and other data-heavy applications. Pagination improves usability by preventing the need to load all data at once, which can slow down the website and overwhelm the user.

59. What are the new APIs provided by the HTML5 standard?

HTML5 introduced several new APIs to enhance web development:

• Canvas API: It allows us to draw and manipulate different graphics on the web.
• Geolocation API: It is very helpful in providing user’s location information through the website used.
• Web Storage API: Offers local and session storage for storing data on the client side.
• Web Workers API: Enables background scripts to run independently of the user interface.
• File API: Allows web applications to access and manipulate files locally.

60. What are the IDEs used for web development?

Popular Integrated Development Environments (IDEs) for web development include:

• Visual Studio Code: One of the most used platforms among all web developers because of its powers, along with its being a very lightweight code editor with extensive plugin support so that it can run on any device.
• Sublime Text: Another text editor which is used a lot by the developers because it is fast and customizable.
• Atom: An open-source editor with a wide range of features and community packages.
• WebStorm: A commercial IDE from JetBrains, specifically designed for JavaScript and web development.
• Brackets: An open-source editor with a focus on web design and front-end development.

61. What is the difference between CSS Grid and Bootstrap Grid?

62. What is hoisting in JavaScript?

When we see the variable and function declarations to be moved towards the top of their containing scope refers to the Hosting in JavaScript during the program compilation. Hence, it means you can use variables and functions before they can be declared in the code.

Example:

In the above code, the declaration var hoistedVar; is hoisted, but its assignment occurs where it is written, hence undefined is logged.

63. What is the purpose of closures in JavaScript?

Closures can allow us to retain access to the lexical scope of a function, i.e. the initial environment in which it is created even after the outer function returns any value. Mostly used for creating private variables and functions.

Example:

In this example, innerFunction forms a closure that keeps access to the count variable even after outerFunction has finished execution.

64. How does PNG differ from SVG formats?

65. What is an event loop in Node.js?

Whenever there is the need to perform non-blocking input-output operations by offloading operations to the system kernel whenever possible, we would use the event loop in Node.js. Therefore, the event loop continuously monitors the call stack to check if there is any function that needs to be executed. Overall it maintains asynchronous code in any application.

66. What is a grid in Bootstrap?

Overall, the grid system is a responsive layout scheme that allows developers to generate complex layouts using rows and columns. The grid in Bootstrap can be adjusted to different screen sizes using predefined classes for various breakpoints. The grid is based on a 12-column system, and it adapts to different screen sizes using predefined classes for various breakpoints.

Example:

In this example, two columns are created, each taking up 6 out of 12 columns, resulting in a 50/50 split. The layout is responsive, adapting to different screen sizes based on the col-md-* class.

67. State difference between Local Storage and Cookies.

68. What are pseudo-classes?

Pseudo-classes in CSS are used to define the special states of an element. They allow you to style elements based on their state or position in the document tree. Common examples include:

• :hover: Applies styles when the user hovers over an element.
• :first-child: Selects the first child of a parent element.
• :focus: Applies styles when an element gains focus, such as when clicked or tabbed into.

69. Explain W3C (World Wide Web Consortium).

The World Wide Web Consortium (W3C) is an international organisation that develops open standards to ensure the long-term growth of the web. Founded by Tim Berners-Lee, the W3C creates standards like HTML, CSS, and XML to promote interoperability and accessibility on the web, ensuring that websites and web applications work consistently across different browsers and devices.

70. What is the use of grouping in CSS3?

Grouping in CSS3 is used to apply the same style rules to multiple selectors, reducing the amount of code and making it easier to maintain. This is done by separating selectors with a comma.

Example:

In this example, the styles are applied to all <h1>, <h2>, and <h3> elements.

71. What is the method used to submit forms in JavaScript?

In JavaScript, the submit() method is used to submit a form programmatically. It can be called on a form element to trigger the form submission.

Example:

72. How does Local Storage differ from Session Storage?

73. What is the use of each() function in jQuery?

The ‘each()’ function in jQuery is used to iterate over a collection of elements or an array. It allows you to perform actions on each element within the collection.

Example:

In this example, all <p> elements are selected and their text color is changed to blue.

74. What are the types of CDNs supported in jQuery?

There are two main types of CDNs (Content Delivery Networks) supported in jQuery:

• Public CDNs: Provided by companies like Google, Microsoft, and Cloudflare, allowing you to load jQuery from a globally distributed network of servers.
• Private CDNs: Companies can set up their own CDN to serve jQuery and other assets, ensuring faster load times for users in specific regions.

75. What is the difference between Cookies and Tokens in Web Security?

76. How do RESTful APIs differ from GraphQL APIs?

77. Describe a challenging web development project you worked on. How did you overcome the difficulties?

I worked on a complex e-commerce site with frequent crashes due to high traffic. I optimised the backend by implementing load balancing and caching, which resolved the performance issues.

78. Can you give an example of a time you had to learn a new technology quickly? How did you manage?

I had to learn React for a project with a tight deadline. I managed by dedicating extra hours to study tutorials and practice coding exercises, quickly grasping the basics and applying them effectively.

79. Describe a situation where you had to collaborate with a team member who had a different working style.

Here you can say, you had collaborated with a designer who preferred a more visual approach, while you focused on code. You both agreed on regular meetings and clear documentation to align our work, which led to a successful project.

80. How do you prioritise your tasks when you have multiple deadlines approaching?

I prioritise tasks based on urgency and impact, breaking them into smaller tasks and tackling high-priority items first. I also communicate with stakeholders to manage expectations.

81. Tell me about a time you identified a bug in your code that no one else noticed. How did you find and fix it?

I discovered a hidden bug during a routine code review. I used debugging tools to trace the issue to a misconfigured variable and fixed it before it reached production.

82. How do you approach testing and debugging your code before deployment?

I write unit tests and use automated testing tools to catch errors. For debugging, I use console logs and browser developer tools to identify and fix issues before deploying the code.

83. Describe a scenario where you had to refactor code. What was the reason, and how did you go about it?

I refactored a legacy codebase that was difficult to maintain. I modularized the code, improved readability, and removed redundant functions, resulting in more maintainable and efficient code.

84. Can you share an experience where you had to optimise a website’s performance? What steps did you take?

I optimised a slow website by compressing images, minifying CSS/JS files, and enabling browser caching. These steps reduced load times and improved the user experience significantly.

85. Can you share a project where you had to integrate third-party APIs? What challenges did you face?

I integrated a payment gateway API into an e-commerce site. The challenge was handling different error responses. I resolved it by implementing thorough error handling and testing to ensure a smooth user experience.

86. How do you handle feedback on your work, especially when it’s critical?

I view critical feedback as an opportunity to improve. I listen carefully, ask questions for clarification, and make necessary adjustments to my work to meet expectations.

Conclusion

In conclusion, web developer interview questions help anyone preparing for web development, providing a solid understanding in both technical and non-technical aspects. Moreover, reading daily blogs regarding web development, research papers, etc, will keep you up-to-date.

In this guide, we covered different aspects of web development, like essential topics, from basic HTML and CSS questions to more advanced concepts like RESTful APIs and JavaScript practices. You can frequently make demo projects and interfaces so that you can have a good amount of practice before your web developer interview. In the end, you can have the right preparation for the interview by understanding all the questions mentioned in this blog.