Top 50 Interview Questions for Web Developer With Answers

In today’s competitive business landscape, there is an increasing demand for web developers. A web developer is a professional who creates websites and ensures the website is visually appealing and easy to navigate. If you are seeking a career as a web developer, you must be well-prepared for web developer interview questions.

In this article, we have mentioned the top 50 interview questions for web developers that will help you with your next interview. You can take online web development certification courses and take your preparation to the next level. So, let us get started.

1. What is the difference between progressive enhancement and graceful degradation?

Ans: This is one of the most important topics in web designer interview questions. Progressive enhancement and graceful degradation are two distinct approaches in web development, both aimed at improving the user experience across different devices and browsers.

It is a strategy that starts with a basic, universally accessible version of a web application or website and then adds more advanced features and enhancements for users with modern browsers or devices. This approach prioritises the core functionality and content, ensuring that it is accessible to all users, including those with older browsers or limited capabilities.

On the other hand, graceful degradation is an approach that begins with a fully-featured and visually rich website or application designed for modern browsers and devices. It then gracefully adapts or degrades its functionality and appearance for users with older or less capable technology.

Graceful degradation starts with a more complex baseline and ensures that the user experience remains acceptable even if certain features or styling are not available on older browsers.

2. Explain CORS (Cross-Origin Resource Sharing).

Ans: CORS, or Cross-Origin Resource Sharing, is a security mechanism implemented by web browsers to regulate how web pages from one domain can access resources hosted on another domain. It is designed to prevent potential security risks and data breaches that could occur if web pages were allowed unrestricted access to resources across different origins.

CORS relies on specific HTTP headers that the server hosting the resources must include in its responses, defining which domains are permitted to make cross-origin requests and specifying the allowed HTTP methods and headers.

This policy helps maintain the integrity of web applications while still enabling legitimate cross-origin interactions, ensuring that data and resources can be securely shared among different web domains when configured correctly.

3. What is the purpose of the Fetch API in JavaScript?

Ans: The Fetch API in JavaScript serves as a modern, standardised way to make network requests, primarily for retrieving data from a server or sending data to a server. Its purpose is to simplify the process of making HTTP requests, both for fetching resources like HTML, JSON, or images from remote servers and for posting data to these servers.

The Fetch API provides a more flexible and promise-based approach compared to older methods like XMLHttpRequest. It enables developers to handle network requests asynchronously, making it easier to build responsive and efficient web applications.

Additionally, it offers a clean and consistent interface for working with requests and responses, making it a fundamental tool for interacting with web services and APIs in modern web development.

Also read: 14+ GitHub Courses To Become A Skilled Web Developer

4. Describe the differences between cookies, sessionStorage, and localStorage.

Ans: Cookies, sessionStorage, and localStorage are three distinct web storage mechanisms in web development, each with its characteristics and use cases.

Cookies are small pieces of data that web servers send to the user's browser, which are then stored locally. They have been around for a long time and are primarily used for persisting small amounts of information like user preferences and tracking data.

Cookies have some limitations, such as a relatively small storage capacity (typically up to 4KB per cookie) and automatic inclusion in every HTTP request to the server, which can impact performance. Additionally, they have security concerns related to cross-site scripting (XSS) and cross-site request forgery (CSRF) attacks.

SessionStorage and localStorage, on the other hand, are newer web storage mechanisms introduced with HTML5. They provide a way to store larger amounts of data (usually up to 5-10MB) on the client side without automatically sending data to the server with each request, addressing some of the limitations of cookies.

SessionStorage is designed for storing data that should be accessible only during a single session. It is scoped to the lifetime of a page session and is cleared when the session ends, such as when the user closes the tab or browser.

This makes it suitable for temporarily storing data like shopping cart contents or form data that should not persist beyond the current session. This is one of the must-know web developer interview questions for freshers.

5. What is a service worker, and how does it enhance web applications?

Ans: A service worker is a JavaScript script that runs in the background of a web application and is separate from the main web page while acting as a proxy between the web application and the network. It is a critical component of Progressive Web Apps (PWAs) and enhances web applications in several ways.

Firstly, service workers enable offline functionality by caching resources like HTML, CSS, JavaScript, and images. This means that even when users are not connected to the internet, they can still access certain parts of the web application, enhancing the user experience.

Secondly, service workers can improve performance by intercepting and managing network requests. They can serve cached content, reducing the need to fetch data from the server, resulting in faster load times and reduced server load.

Additionally, service workers enable push notifications, allowing web applications to send real-time updates to users even when the application is not open in the browser. This enhances user engagement and keeps users informed about important events or updates.

6. Explain the concept of event delegation in JavaScript.

Ans: Event delegation is a concept in JavaScript where instead of attaching an event listener to individual elements, you attach a single event listener to a common ancestor element that contains multiple child elements. When an event occurs on one of these child elements, it bubbles up to the ancestor element, which can then determine which specific child element triggered the event.

This approach is more efficient, especially in scenarios with many dynamically generated elements, as it reduces the number of event listeners and memory usage. Event delegation simplifies code maintenance and enhances performance by handling events at a higher level in the DOM tree, making it a valuable technique for building responsive and scalable web applications.

Also read: 25 Free Web Development Courses Online You Must Do

7. What is the purpose of the defer attribute in a script tag?

Ans: The defer attribute in a script tag serves a crucial purpose in web development. When included in an HTML script tag, it instructs the browser to defer the execution of the JavaScript code until after the HTML document has been fully parsed and loaded. This is particularly useful for optimising web page loading performance.

By deferring script execution, the browser can continue parsing and rendering the rest of the page's content without being blocked by JavaScript execution. This can result in faster page rendering and a better user experience, especially on slower internet connections.

The defer attribute is commonly employed when the order of script execution does not matter, and it allows web developers to strike a balance between script functionality and page load speed.

8. Explain the differences between REST and GraphQL APIs.

Ans: This is one of the frequently asked Web development viva questions. REST (Representational State Transfer) and GraphQL are two different approaches to designing and interacting with APIs. REST is an architectural style for building web services, while GraphQL is a query language for APIs.

In a REST API, data is exposed through a predefined set of endpoints, each representing a resource (e.g., /users, /products) and supporting a limited set of HTTP methods (GET, POST, PUT, DELETE). Clients often need to make multiple requests to different endpoints to fetch related data, which can lead to over-fetching or under-fetching of data.

REST APIs are generally easier to understand and use due to their simplicity, making them a good choice for straightforward use cases. On the other hand, GraphQL allows clients to request precisely the data they need and nothing more.

Clients can send queries that specify the structure of the response, allowing them to fetch multiple types of data in a single request and avoiding over-fetching. This flexibility is particularly beneficial for mobile apps and frontend applications where network efficiency is crucial.

However, implementing a GraphQL API requires defining a schema and resolver functions to handle queries and mutations, which can be more complex than setting up a REST API. Additionally, GraphQL does not prescribe a specific URL structure or HTTP methods, making it more flexible but requiring careful consideration of security concerns.

Also read: 17+ Courses on HTML5 for Beginners to Become a Web Developer

9. What is the purpose of the viewport meta tag in HTML?

Ans: The viewport meta tag in HTML serves a crucial role in ensuring that web pages are displayed properly on a variety of devices with different screen sizes and resolutions. It allows web developers to control how the browser should render and scale the content within the viewport, which is the visible portion of the web page on the user's screen.

By specifying attributes like width, initial scale, and maximum scale, developers can create a responsive design that adapts to various devices, such as smartphones, tablets, and desktop computers.

This tag is particularly important for mobile optimization, as it enables web pages to be more user-friendly and accessible, enhancing the overall user experience by ensuring that content is appropriately sized and readable on all screens. In essence, the viewport meta tag plays a fundamental role in making websites visually appealing and functional across a wide range of devices.

10. Explain the concept of "hoisting" in JavaScript.

Ans: In JavaScript, "hoisting" is a behaviour that allows variable and function declarations to be moved to the top of their containing scope during the compilation phase, even though their actual assignments or definitions may appear later in the code.

This means that you can use variables and functions before they are formally declared in your code, although it is important to note that only the declarations are hoisted, not the initializations or assignments. Variables declared with var are hoisted to the top of their function or global scope, while those declared with let and const are hoisted to the top of their block scope.

Understanding hoisting is crucial because it can lead to unexpected behaviour if not managed properly, and it highlights the importance of declaring variables and functions at the beginning of their scope for code clarity and predictability. This is another one of the frequently asked web developer interview questions and answers.

11. Explain the differences between null and undefined in JavaScript.

Ans: In JavaScript, both null and undefined represent the absence of a value, but they are used in slightly different contexts and have distinct meanings. Undefined is a primitive data type and a special value that indicates a variable has been declared but has not been assigned a value yet, or when a function does not explicitly return a value.

It can also be the default value of function parameters. On the other hand, null is also a primitive value, but it represents an intentional absence of any object value. It is often used when you want to explicitly indicate that a variable or object property should have no value or be empty.

While both null and undefined are false values in JavaScript, understanding their differences is important for writing clean and error-free code.

12. What is the purpose of the rel="noopener" attribute in anchor (<a>) tags?

Ans: This question is considered one of the interview questions for web developers. The rel="noopener" attribute in anchor (<a>) tags serves an important purpose in web development. It is primarily used to enhance security and prevent potential security vulnerabilities when opening links in a new tab or window.

When a link with target="_blank" is clicked, a new browsing context is created, and the page that opened the link retains some control over the newly opened tab or window. This control could potentially be exploited by malicious websites to manipulate or access the opener window.

By including rel="noopener" in the anchor tag, web developers instruct the browser to ensure that the newly opened tab or window has no access to the referring tab or window. This helps to mitigate potential risks associated with cross-tab/window scripting attacks, protecting user data and privacy.

It is a recommended best practice to use rel="noopener" whenever you have links with target="_blank" to ensure a more secure and safer browsing experience for users.

Also read: Want to Pursue a Career in Web Development? Pursue these 18+ Online Courses for Beginners

13. How does the lazy loading of images improve web performance?

Ans: Lazy loading delays the loading of images until they are visible in the viewport, reducing initial page load times and conserving bandwidth.

14. Explain the concept of "closure memory leaks" in JavaScript.

Ans: In JavaScript, a "closure memory leak" occurs when a function, often referred to as a closure, retains references to variables or objects in its lexical scope even after it has finished executing. Because these references are held by the closure, they cannot be garbage collected, potentially leading to increased memory usage in a web application.

This issue typically arises when closures are created within loops or event handlers, and they capture references to variables or objects that are no longer needed, but the closures persist in memory, preventing those resources from being freed.

Developers need to be mindful of managing closures and their captured variables to avoid memory leaks, often by explicitly nullifying or detaching references when they are no longer required, ensuring efficient memory usage in JavaScript applications.

15. What are WebSockets, and why are they useful in web development?

Ans: One of the most asked web development viva questions is about WebSockets. It provides full-duplex communication channels over a single TCP connection, enabling real-time, bidirectional communication between the server and the client. They are valuable for building interactive and responsive web applications.

16. What is the difference between CSS Grid and Flexbox, and when would you use each one?

Ans: CSS Grid and Flexbox are two layout systems in CSS, each with its strengths and use cases. CSS Grid is primarily designed for two-dimensional layouts, making it ideal for creating complex grid structures. It allows you to define rows and columns, creating a grid where you can precisely position and size elements.

Grid is well-suited for creating both simple and complex layouts, such as web page templates, magazine-style designs, and data tables. It excels at aligning items both horizontally and vertically, making it a powerful choice for responsive designs where content needs to adapt to different screen sizes.

On the other hand, Flexbox (or the Flexible Box Layout) is designed for one-dimensional layouts, making it perfect for arranging elements along a single axis, either horizontally or vertically. It excels at distributing space within a container and aligning items along the axis.

Flexbox is great for creating components like navigation bars, menus, and lists, where the content within a container needs to adapt dynamically based on the available space. It is particularly useful for creating responsive designs for items with varying content lengths, ensuring they align and size correctly.

In summary, use CSS Grid when you need to create complex two-dimensional layouts with precise control over rows and columns. Use Flexbox when you want to arrange items along a single axis, making it easy to create responsive and flexible designs for components within a container.

In practice, many layouts benefit from a combination of both CSS Grid and Flexbox to leverage their respective strengths for different parts of a web page or application.

17. Explain the concept of "event bubbling" and "event capturing" in JavaScript.

Ans: In JavaScript, event bubbling and event capturing are two phases of the event propagation process that occurs when an event is triggered on a DOM (Document Object Model) element, such as a button or a div. Event bubbling is the default behaviour in which an event starts from the target element that triggered it and then bubbles up through its parent elements in the DOM hierarchy.

This means that the innermost element's event handlers are executed first, followed by its parent elements' event handlers in ascending order. In contrast, event capturing is the opposite process, where the event starts from the top of the DOM hierarchy and trickles down to the target element.

You can control which phase you want to capture events in by specifying the third argument in the addEventListener method. Understanding event bubbling and capturing is crucial for managing and handling events effectively in web applications, allowing developers to control how events propagate through the DOM tree and handle them accordingly.

18. What is the purpose of the async and await keywords in JavaScript?

Ans: The async and await keywords in JavaScript are used to work with asynchronous code in a more structured and readable manner. Asynchronous operations, such as fetching data from a server or reading a file, often involve delays or unpredictable timing.

Instead of using callback functions or managing promises directly, async and await provide a more intuitive way to handle asynchronous tasks. The async keyword is used to declare a function as asynchronous, indicating that it will return a promise. Inside an async function, you can use the await keyword before an expression that returns a promise.

This allows the program to pause execution at that point until the promise is resolved, effectively making asynchronous code look more like synchronous code. It simplifies error handling as well, as you can use try-catch blocks to handle exceptions familiarly.

In essence, async and await improve the readability and maintainability of asynchronous JavaScript code, making it easier to write and understand complex operations that involve asynchronous tasks, ultimately leading to more maintainable and less error-prone code.

19. Explain the concept of "caching" in web development and its benefits.

Ans: Caching in web development refers to the process of storing and reusing previously fetched data or resources to optimise performance and reduce the load on web servers. It involves temporarily storing copies of web content, such as HTML pages, images, stylesheets, and JavaScript files, either on the user's device (client-side caching) or on intermediate servers (server-side caching).

Caching offers significant benefits, including faster page load times, reduced server load, and improved user experience. When a user revisits a website, cached content can be quickly retrieved, reducing the need for repeated requests to the server.

This not only speeds up page rendering but also conserves bandwidth and lowers server processing overhead. Effective caching strategies are crucial for scaling web applications and ensuring they remain responsive and efficient, particularly in high-traffic scenarios.

20. What is the difference between a "cookie" and a "web storage" in terms of data storage capabilities?

Ans: The difference between a cookie and web storage is considered one of the most asked web designer interview questions. Cookies and web storage are two distinct mechanisms for storing data in web applications, each with its own set of capabilities.

Cookies: These are small pieces of data sent from a web server and stored on a user's device, typically in the user's web browser. They have been around for a long time and are primarily used for maintaining state and session information, such as user authentication tokens and user preferences.

Cookies have a limited storage capacity, usually around 4KB per cookie, and they are automatically sent with every HTTP request to the server, which can add to the data transfer overhead. Additionally, cookies are subject to security and privacy concerns, as they can be accessed by both the server and potentially malicious scripts on the client side.

Web Storage: It refers to the HTML5 Storage API, which includes two mechanisms: localStorage and sessionStorage. These provide a more modern and capable way to store data on the client side. localStorage allows developers to store larger amounts of data (typically up to 5-10MB per domain) persistently across browser sessions, making it suitable for caching and offline data storage.

Session storage is similar but limited to storing data for the duration of a single-page session. Unlike cookies, data stored in web storage is not automatically sent to the server with every HTTP request, reducing data transfer overhead.

However, web storage is still subject to the same-origin policy, limiting access to data stored by other websites to enhance security.

21. What is the purpose of the prefetch and preload attributes in HTML?

Ans: This is amongst the top interview questions for web developers. The prefetch and preload attributes in HTML serve distinct purposes, both aimed at optimising web page performance and user experience.

The prefetch attribute is used to indicate resources that a web page might need in the future but is not immediately required to render the current page. When a browser encounters a prefetch attribute, it begins downloading the specified resource in the background, reducing latency when the resource is needed.

This can include things like fonts, scripts, or stylesheets that may be needed on subsequent pages or after user interactions. On the other hand, the preload attribute is used to signal critical resources that are essential for rendering the current page correctly.

By specifying resources with preload, you tell the browser to prioritise downloading and caching these resources, ensuring that the page can be displayed as quickly as possible. This is particularly useful for vital assets like the main stylesheet or scripts required for interactivity.

22. What is the "box model" in CSS, and how does it affect layout?

Ans: The box model in CSS defines how elements are displayed on the web page by considering the content area, padding, border, and margin. Understanding the box model is essential for precise control over element dimensions and spacing.

The box model plays a crucial role in affecting the layout of elements on a web page. Here is how it impacts layout:

Element Sizing: The box model determines how the size of an element is calculated. When you set the width and height of an element, you are primarily defining the size of the content area. This affects how much space the content can occupy within the element.

If you have padding and borders, they add to the total size of the element, so understanding the box model helps you control how much space an element takes up in your layout.

Spacing and Alignment: The padding, border, and margin components of the box model provide the necessary spacing and alignment tools for elements. Padding creates space between the content and the border, which can be used to control how text or images are positioned within an element.

Borders define the visual boundaries of an element, helping to separate it from neighbouring elements. Margins set the space between elements, influencing their placement and alignment in the layout.

Responsive Design: In responsive web design, the box model is instrumental in controlling how elements adapt to different screen sizes and devices. By adjusting the content, padding, and margins, you can create layouts that respond fluidly to various viewport sizes. This allows for a better user experience on both desktop and mobile devices.

23. Explain "minification" and "compression" in the context of web performance optimization.

Ans: Minification and compression are two essential techniques used in web performance optimisation to reduce the load times of web pages. Minification involves the process of removing unnecessary characters, spaces, and line breaks from the source code of web files, such as HTML, CSS, and JavaScript.

This results in smaller file sizes, which can be downloaded and executed by browsers more quickly.

Minification does not affect the functionality of the code but helps to minimise the bandwidth required for transmitting the files, ultimately improving page load times. Compression, on the other hand, is the practice of reducing the size of web files by using compression algorithms such as GZIP or Brotli.

These algorithms work by encoding the file data more efficiently, resulting in significantly smaller file sizes. When a browser requests a compressed file, the web server sends the compressed version, and the browser decompresses it for use.

This not only reduces bandwidth usage but also speeds up the delivery of resources to the user's browser, contributing to a faster and more responsive web experience. This type of interview questions for web developers is considered the most commonly asked interview question.

24. What is "lazy loading" in JavaScript, and why is it beneficial?

Ans: Lazy loading is a technique where certain parts of a web page (usually images or scripts) are loaded only when they are needed, which can significantly improve page load speed and user experience. This type of web development questions and answers will test different approaches to web development.

25. What are "HTTP status codes," and can you provide examples of a few common ones?

Ans: HTTP status codes are three-digit numbers returned by a web server to indicate the outcome of an HTTP request. Examples include 200 (OK), 404 (Not Found), and 500 (Internal Server Error).

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26. Explain the concept of "memoisation" in JavaScript and how it can improve performance.

Ans: Memoisation is a performance optimisation technique in JavaScript (and many other programming languages) that involves caching the results of expensive function calls and reusing them when the same inputs are encountered again.

Instead of recomputing the same result multiple times, a memoised function checks if it has already computed and stored the result for a given set of inputs. If it has, it returns the cached result, saving computational time and resources. This technique is particularly useful for functions with high time complexity or those that are frequently called with the same arguments.

By avoiding redundant computations, memoization can significantly improve the overall performance of an application, making it more efficient and responsive, especially when dealing with complex recursive algorithms or data-intensive tasks such as recursive Fibonacci calculations or recursive traversal of trees and graphs. You must practise this type of web designer interview questions for your interviews.

27. What is the "same-origin policy" in web security, and how does it impact cross-origin requests?

Ans: The same-origin policy is a security feature that restricts web pages from making requests to a different domain than the one that served the web page. It helps prevent malicious code from making unauthorised requests to other domains.

The same-origin policy significantly impacts cross-origin requests by imposing restrictions on web applications when they attempt to access resources located on a different origin. These restrictions are in place to enhance web security and protect against various types of attacks.

Here is how the same-origin policy impacts cross-origin requests in more detail:

Blocked by Default: By default, web browsers strictly enforce the same-origin policy, which means that cross-origin requests are blocked. If a web page or script tries to make an HTTP request (e.g., via XMLHttpRequest or the Fetch API) to a resource on a different origin, the browser will prevent it from going through.

This helps prevent unauthorized access to sensitive data or actions on another website.

No Access to Response Data: When a cross-origin request is blocked, the web page making the request does not have access to the response data. This means that the content of the response (e.g., the HTML, JSON, or XML data) cannot be read or processed by the requesting page.

Cookies and Authentication: Cookies and authentication information associated with a specific origin are not automatically sent in cross-origin requests. This is a crucial aspect of the same-origin policy. If these cookies and credentials were included in cross-origin requests, it could potentially lead to unauthorized access to a user's account on another website.

Scripts and DOM Access: JavaScript code running on a web page can interact with the Document Object Model (DOM) of the same origin, but it cannot access the DOM of a different origin. This is another layer of protection that prevents cross-site scripting (XSS) attacks and other security vulnerabilities.

Security Headers and CORS: To enable controlled cross-origin requests, web servers can include specific HTTP response headers like CORS (Cross-Origin Resource Sharing) headers. These headers indicate which origins are allowed to access their resources. If a server does not include the appropriate CORS headers, the browser will block cross-origin requests.

28. Explain the differences between "display: inline-block" and "display: inline" in CSS.

Ans: In CSS, the display property plays a crucial role in determining how elements are rendered on a web page, and understanding the differences between "display: inline-block" and "display: inline" is essential. When you apply display: inline to an element, it transforms it into an inline-level element, similar to text or inline images.

It does not create a new block-level box, which means it would not accept width and height properties. Additionally, margins and padding only impact the left and right sides of the element, not the top and bottom. On the other hand, when you use display: inline-block, it turns the element into an inline-level block container.

This allows it to accept width and height properties, making it possible to control its size. It also allows you to apply margins and padding on all sides of the element.

This combination of inline-level behaviour with block-level properties provides a flexible layout option, commonly used for creating inline blocks of content, such as buttons or grid items. This is one of the most frequently asked web developer interview questions for freshers.

29. What is the purpose of the z-index property in CSS, and how does it affect stacking order?

Ans: The z-index property in CSS is used to control the stacking order of elements within a web page. It is particularly useful when dealing with overlapping elements, such as those positioned with CSS properties like position: absolute, position: relative, or position: fixed.

The z-index property assigns a numerical value to an element, determining its position along the Z-axis, which is a hypothetical axis that extends perpendicular to the screen. Elements with higher z-index values will be placed in front of elements with lower values. This property is crucial for creating layered layouts and managing the visual hierarchy of web page elements.

It allows web developers to precisely control which elements appear in front of or behind others, helping to ensure that the user interface is both functional and visually appealing.

30. What is the "shadow DOM" in web development, and why is it important for encapsulation?

Ans: Another one of the most important web development viva questions is this topic. The shadow DOM is a part of the DOM tree that is encapsulated and isolated from the main document DOM. It is essential for creating reusable web components with encapsulated styling and behaviour.

Also Read: Top 5 Java Web Development Technologies to Master

31. What is a "Content Security Policy" (CSP), and how does it enhance web security?

Ans: CSP is a security feature that helps prevent cross-site scripting (XSS) and other code injection attacks by specifying which scripts and resources are allowed to run on a web page. It adds an additional layer of security by controlling what can be executed.

32. What is the purpose of the async attribute in a script tag, and how does it affect script loading?

Ans: The async attribute in a script tag serves a crucial purpose in web development by controlling how a script is loaded and executed within an HTML document. When you include a script in an HTML page with the async attribute, it indicates to the browser that the script is not critical for the page's rendering and can be loaded asynchronously.

This means that the browser will continue parsing and rendering the HTML content without waiting for the script to download and execute. As a result, the async attribute speeds up the loading of web pages, as it allows multiple resources, such as stylesheets and images, to be fetched in parallel while the script is being downloaded.

However, it is essential to note that the order in which asynchronous scripts are executed is not guaranteed to be the same as their appearance in the HTML document, potentially leading to race conditions if scripts depend on one another.

Therefore, async is most suitable for scripts that are standalone and do not rely on other scripts or the DOM being fully ready.

33. Explain the concept of "bundling" and "minification" in the context of JavaScript and CSS optimization.

Ans: "Bundling" and "minification" are two crucial optimisation techniques used in web development to enhance the performance and efficiency of JavaScript and CSS files. Bundling involves combining multiple individual JavaScript or CSS files into a single, larger file.

This reduces the number of HTTP requests made by a web page, which is beneficial because each request incurs a small overhead. By bundling files, web developers can reduce this overhead, leading to faster page load times.

On the other hand, "minification" involves the process of removing unnecessary characters such as whitespace, and comments, and sometimes even shortening variable and function names in the code.

This reduction in file size not only saves bandwidth but also improves load times since smaller files download more quickly. Minification is especially effective for JavaScript and CSS files because it does not affect the code's functionality but significantly reduces the file size.

34. What is the "viewport" in responsive web design, and how is it defined in HTML?

Ans: Another one of the commonly asked interview questions for web developers is this question. The viewport is the visible area of a web page in the user's browser window. It can be defined in HTML using the <meta name="viewport"> tag with attributes like width, initial scale, and user-scalable to control how the page is displayed on different devices.

35. Explain the concept of "code splitting" in JavaScript and how it improves web performance.

Ans: Web designer interview questions cannot be complete without this one topic where the concept of code splitting is asked. Code splitting is a technique used in JavaScript to improve web performance by breaking down a large JavaScript bundle into smaller, more manageable pieces.

Instead of sending the entire application code to the user's browser when they load a webpage, code splitting allows developers to split the code into smaller chunks, which are loaded on-demand as the user interacts with the application.

This reduces the initial page load time, as only the essential code needed for the initial view is delivered, while additional code is fetched as needed.

This approach not only enhances the user experience by making web applications faster and more responsive but also helps conserve bandwidth and reduces the amount of processing required by the browser, resulting in a more efficient and performant web application.

36. What are "web components" in web development, and how do they promote reusability?

Ans: Web components are a set of technologies that allow you to create reusable and encapsulated custom HTML elements. They consist of custom elements, shadow DOM, and HTML templates, making it easier to build and maintain complex UI components.

37. What is the "Critical Rendering Path," and how does it impact web page loading speed?

Ans: The Critical Rendering Path (CRP) is the sequence of steps the browser follows to render a web page. Optimising the CRP by minimising render-blocking resources and rendering critical content first is essential for improving page loading speed and user experience.

38. Explain the differences between the GET and POST HTTP methods.

Ans: The differences between the GET and POST HTTP methods is considered one of the commonly asked web development questions and answers. GET is primarily used for retrieving data from a web server. When a client sends a GET request, it appends parameters and data to the URL, making them visible in the address bar.

This method is suitable for idempotent operations, meaning they do not have side effects on the server or the data. GET requests are often cached, bookmarked, and easily shareable, but they have limitations on the amount of data they can send, making them less suitable for transmitting large or sensitive data.

On the other hand, POST is designed for submitting data to a server to create or update a resource. In a POST request, data is sent in the request body, so it is not visible in the URL. This method is used when the operation has side effects, such as modifying server data or submitting a form.

POST requests are not cached, and they are more secure for sensitive information or large data payloads. They are typically used for actions like submitting forms, uploading files, or making changes to a server's database.

39. What is "Cross-Site Scripting" (XSS), and how can it be prevented in web applications?

Ans: XSS is a security vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users. It can be prevented by sanitising user input, using content security policies (CSP), and escaping output data.

40. What is the purpose of the aria-* attributes in HTML, and how do they enhance web accessibility?

Ans: The "aria-*" attributes in HTML, which stand for Accessible Rich Internet Applications, serve a crucial role in enhancing web accessibility for individuals with disabilities. These attributes are used to provide additional information to assistive technologies such as screen readers, making web content more understandable and navigable for users who may have visual or cognitive impairments.

They supplement standard HTML elements by conveying information about the roles, states, and properties of various elements on a webpage. For example, the "aria-label" attribute can be used to provide a descriptive label for elements like buttons or links, ensuring that screen reader users understand their purpose even if the visible text is not sufficiently informative.

Similarly, attributes like "aria-hidden" help hide decorative or non-essential elements from assistive technologies to reduce confusion.

41. Explain the "same-site" attribute in cookies and how it can improve security.

Ans: The “same-site” attribute in cookies is considered the most asked web development viva questions. The "same-site" attribute in cookies is a security feature that helps improve web application security by controlling when cookies should be sent in cross-site (cross-origin) requests.

By setting the "same-site" attribute, developers can specify whether a cookie should only be sent with requests originating from the same site (or "same-origin"), thereby mitigating certain types of security threats. When you set the "same-site" attribute to "Strict," the cookie is only sent with requests that originate from the same site, ensuring that it would not be included in cross-site requests.

This helps protect against Cross-Site Request Forgery (CSRF) attacks. Alternatively, when "same-site" is set to "Lax," cookies are still sent in cross-site requests, but only for top-level navigations (e.g., clicking a link or entering a URL in the browser's address bar). This allows for a balance between security and usability.

Cookies with the "None" value for "same-site" are sent with all requests, including cross-origin ones, but should only be used when secure attributes such as "Secure" (for HTTPS-only) and "Secure" (for secure connections) are also applied to the cookie to prevent information leakage and session hijacking.

42. What is the purpose of the CORS preflight request in cross-origin AJAX requests, and when is it triggered?

Ans: The CORS (Cross-Origin Resource Sharing) preflight request serves a crucial role in securing cross-origin AJAX (Asynchronous JavaScript and XML) requests and preventing potentially harmful cross-site requests. When a web page hosted on one domain (origin) attempts to make an AJAX request to a different domain, the same-origin policy implemented by browsers typically restricts such requests for security reasons.

However, CORS is a mechanism that allows web servers to specify which domains are permitted to access their resources. The purpose of the preflight request is to check with the target server whether the actual request (the one containing the actual data or action) is safe to send.

This is necessary when certain conditions are met, such as the presence of custom headers, content types other than the most common ones (e.g., application/json or text/plain), or when using certain HTTP methods like PUT or DELETE, which are considered non-simple methods.

The preflight request, which is an HTTP OPTIONS request, is automatically triggered by the browser before the actual AJAX request when these conditions are met. It includes information about the intended actual request, such as the HTTP method and headers, to request permission from the target server.

43. What is a "Single Page Application" (SPA), and what are its advantages and disadvantages?

Ans: An SPA is a web application that loads a single HTML page and dynamically updates the content as the user interacts with it. Advantages include a smoother user experience and reduced server load, but disadvantages may include SEO challenges and initial load times.

44. Explain the "box-shadow" property in CSS and how it is used to create visual effects.

Ans: Web designer interview questions cannot be complete without this question where the box-shadow property in CSS is asked. The "box-shadow" property in CSS is a powerful tool for adding visual depth and dimension to web page elements.

It allows web developers to create effects that simulate shadows or glows around elements, making them appear to float above the background or cast shadows on the page. The property accepts several values, including horizontal and vertical offsets, blur radius, spread radius, and colour.

By adjusting these values, designers can achieve a wide range of shadow effects, from subtle and soft to bold and dramatic. For instance, to create a subtle shadow effect for a paragraph, you can apply "box-shadow" with values like horizontal and vertical offsets, blur radius, spread radius, and a colour of your choice.

This property is essential for enhancing the visual appeal of web designs and improving the user experience by adding depth and visual interest to elements on the page.

45. What is the difference between "localStorage" and "sessionStorage" in web storage, and when would you use each one?

Ans: localStorage and sessionStorage are both web storage options in JavaScript that allow you to store data on the client side (in the user's browser) without the need for server-side storage or cookies. The key difference between them lies in their lifespan and scope.

localStorage stores data with no expiration date, meaning the data persists even after the user closes the browser or navigates away from the website. This makes it suitable for storing long-term data like user preferences, settings, or cached content that should be available across multiple sessions.

On the other hand, sessionStorage is designed for temporary storage. It keeps data only for the duration of a single-page session. When the user closes the browser tab or navigates away from the page, the data is automatically cleared.

This makes it ideal for storing information that is needed temporarily, such as data used during a user's current visit or session, like shopping cart contents or form data that should not persist between page reloads.

46. What is the "Content Delivery Network" (CDN), and how does it enhance web performance?

Ans: A CDN is a network of geographically distributed servers that deliver web content to users from the nearest server. It improves performance by reducing latency, distributing traffic, and caching content, resulting in faster page loads.

47. Explain the "MVC" (Model-View-Controller) architectural pattern and its application in web development.

Ans: The Model-View-Controller (MVC) architectural pattern is a fundamental framework in web development, designed to enhance the organisation and maintainability of web applications. In MVC, the application is divided into three interconnected components: the Model, View, and Controller. The Model represents the application's data and business logic, managing data retrieval, processing, and storage.

The View is responsible for the user interface, displaying data to users through HTML, CSS, and often templates or view engines. Lastly, the Controller acts as a bridge between the Model and the View, handling user input from the View, processing it, and instructing the Model accordingly.

This separation of concerns makes it easier to manage and scale web applications, allowing developers to modify one component without affecting the others.

48. What is "Cross-Origin Resource Sharing" (CORS), and how can it be configured on the server to allow cross-origin requests?

Ans: CORS is a security feature that enables or restricts web pages from making requests to different domains. To configure CORS on the server and allow cross-origin requests, you typically need to set appropriate HTTP headers, including "Access-Control-Allow-Origin," "Access-Control-Allow-Methods," and "Access-Control-Allow-Headers." These headers specify which origins, methods, and headers are permitted to access resources on the server.

49. Explain the concept of "promises" in JavaScript and how they simplify asynchronous code.

Ans: Promises are a crucial concept in JavaScript for simplifying the handling of asynchronous operations. When dealing with tasks that may take time to complete such as fetching data from a server or reading files, promises provide a structured and organised approach.

They represent a value that could be available in the future, either successfully resolved with a result or rejected with an error. Promises have three states: pending, fulfilled (resolved), and rejected, and they allow developers to chain asynchronous operations together using .then() and .catch() methods.

This chaining simplifies complex sequences of asynchronous tasks, making code more readable and manageable. Promises also support functions such as Promise.all() and Promise.race() to coordinate multiple asynchronous operations concurrently or handle the first resolved promise in a group.

50. What is the "viewport meta tag" in HTML, and how can it be used to make a website responsive?

Ans: This is one of the essential web designer interview questions to be asked in interviews. The viewport meta tag, when properly configured, allows web developers to control how a web page is displayed on different devices.

By specifying attributes like width, initial scale, and user scalability, you can optimise the viewport settings for responsiveness, ensuring that the content scales and fits various screen sizes.

Conclusion

Web development is a competitive field, and the only way to get ahead is to be well-prepared for job interviews. We hope this article on interview questions for web developers has provided you with important and helpful guidance on how to answer them.

As long as you practise your answers in advance, you will stay confident during the interview, and showcase your technical knowledge. These interview questions for web developers will help in strengthening your career while giving you an idea for your next interview.