Top 50 Web Development Interview Questions: From Basics to Advanced

The surge in digitalisation, the exponential growth of e-commerce, the increasing need for mobile responsiveness, advancements in technology, expanding opportunities for remote work, and growing concerns about cybersecurity have collectively heightened the demand for web developers. For individuals seeking employment in web development or aiming to advance their careers in the field, familiarity with common web development interview questions and answers is invaluable. This knowledge not only enables candidates to articulate their skills effectively but also demonstrates a comprehensive understanding of key concepts. Likewise, students and learners in the field of web development can derive significant benefits from this insight, directing their focus towards essential topics and preparing them for real-world scenarios.

Individuals looking to change their careers and transition into web development recognize the significance of understanding interview questions as a valuable tool for showcasing how their existing skills align with the industry’s demands. Furthermore, interviewers and employers benefit from gaining valuable insights to assess candidates more effectively, ensuring a match between the required skills and a candidate’s capabilities.

Educators and trainers also find these questions instrumental in aligning their curriculum with industry expectations. In essence, web development interview questions and answers serve as a valuable resource for a spectrum of individuals, including candidates, educators, interviewers, and human resources professionals, fostering a more informed and confident hiring process. Let’s acquaint ourselves with the significantly vital web development interview questions and answers and thoroughly prepare for success.

Web Development Interview Questions for Beginners: Essential Basics Every Developer Must Know

1. What is HTML, and why is it important to web development?

HTML is the base of web pages. Every heading, button, or other element on a webpage depends on HTML. It is just like making a skeleton of a page where we design and define areas for images, text, and forms.

HTML is important because, without it, a browser would not know how to structure and display content.

2. Explain the purpose of HTML tags and give some examples of important structural tags.

HTML uses tags that inform the browser how to render content contained within it. Every tag has a specific purpose for example: to define heading, paragraph or an image.

Below are some examples of key structural tags:

• <h1> up to <h6>: These will be the headings for your webpage and will determine that the first is the biggest and the sixth the smallest one.
• <p>: Defines the paragraph of your text.
• <img>: Adds image. Don’t forget to include the src (source) and alt (alternate text) attributes.
• <a>: Insert a hyperlink. The href attribute links to where the link wants to lead.

Example:

Output:

3. What is CSS? Describe how it makes your page look better.

This basically defines how HTML’s elements should look. If HTML defines the skeleton, CSS dictates the aesthetics, meaning to add color, font type, layouts, and sometimes animations to a web page.

4. How does CSS Flexbox layout work for responsive designs?

The CSS Flexbox is one layout module that allows putting elements of any size in a flexible container. It proves very effective in making the website responsive since Flexbox automatically works out the dimensions for setting the layout by the variations of the screens and sizes on the display devices.

5. List the primary data types in JavaScript.

JavaScript data types are the different kinds of data we work with. The main types are:

• String: Text values, like “Hello World”.
• Number: Numeric values, both integer and floating-point.
• Boolean: true or false, often used in conditions.
• Object: Complex data structures like {name: “Arjun”, age: 25}.
• Array: Lists of values, like [1, 2, 3].

DOM presents an HTML document as a tree of nodes. This means that every element on the page is a node and can be accessed with JavaScript.

Let’s update the text of a paragraph with JavaScript:

Here, when we click the button, JavaScript targets the paragraph’s id and changes its text.

7. Describe the difference between block-level and inline elements in HTML.

All HTML elements are either block-level or inline:

• Block-level elements take the entire width of a container and begin new lines. Such as <div>, <p>, <h1> etc.,
• Inline elements only take the amount of width they need to fill and will not cause the line of text to break. For example: <span>, <a>, <img>.

8. Explain the purpose of the <DOCTYPE> declaration in HTML.

The <DOCTYPE> declaration lets the browser know we are using what version of HTML. It ensures our page will load just as quickly in any browser. For HTML5, we declare it this way:

<!DOCTYPE html>

Using the <DOCTYPE> declaration, we avoid the “quirks mode” that some browsers are prone to that can render our styling and behaviour odd in certain situations.

9. What is the difference between internal, external, and inline CSS?

There are three ways that we can add CSS to HTML:

• External CSS: Called as a separate file, which lets us apply styles to many pages off of one stylesheet.
• Internal CSS: Added inside the <style> tag inside the <head>. Used for page-specific styles.
• Inline CSS: Included right in an HTML element with the style attribute. Best suited for one-time quick modifications.

Also read: Top CSS Interview Questions and Answers

10. How would you access the source code of a webpage in different browsers?

Looking at the source code of a webpage lets us know its structure. Each major browser has an inspection tool to do that:

• For Chrome/Edge, we can right-click and go to Inspect or just use Ctrl+Shift+I.
• For Firefox, we right-click and go to Inspect Element or Ctrl+Shift+I.
• In Safari, we go to Preferences > Enable Developer mode and then Option+Cmd+I.

Within these inspection tools, we can see and even make changes to HTML and CSS in real-time, seeing what they look like without having to edit the files themselves.

11. What are the primary differences between HTML and XHTML?

Both structure web pages, but XHTML is stricter and follows stricter XML rules.

HTML is more forgiving, which means you can skip closing tags like <br> without causing errors. XHTML doesn’t allow this. Every tag needs a closing tag or self-closing syntax like <br />.

Here’s a quick comparison:

12. Explain what responsive design is and how CSS media queries work.

Responsive design makes sure that our web pages are responsive to the device, changing the content, layouts, and images according to the screen size.

CSS media queries will be able to detect the viewport size and apply specific styles under certain conditions.

13. What is an API, and why are APIs used in web development?

APIs, or Application Programming Interfaces, are simply connectors. They let different software applications talk to each other.

Think of them as translators that let different systems exchange information and work together.

APIs in web development often bring in data from outside sources—like showing live weather, payment processing, or connecting with social media.

With APIs, we can do more than just create static pages; we build dynamic, interactive experiences.

14. Explain how AJAX works and its role in improving user experience.

AJAX (Asynchronous JavaScript and XML) refreshes pages without reloading. Through AJAX, a web page can send a request to a server in the background.

That means only specific parts of a page get updated while everything else stays in place.

15. What is the difference between GET and POST requests in HTTP?

GET and POST requests in HTTP are nothing but methods used to send data between a browser and a server. They work very differently:

1. GET requests to fetch data from a server.

• The data is visible in the URL (e.g., example.com/page?query=value).
• Best for retrieving data without affecting it.

2. POST requests send data to the server to be processed.

• Data is not visible in the URL, which makes it a better choice for sensitive information.
• Used when you’re submitting a form, uploading a file, or logging in.

16. How does CORS (Cross-Origin Resource Sharing) function?

Browsers, for safety reasons, block web pages to make requests to a different domain. CORS allows us permission-set, telling the browser which external resources are all right to access.

If you are pulling resources from another domain, then you’ll want the server to set some headers, such as Access-Control-Allow-Origin.

If that’s not being set, the browser isn’t going to load from that domain.

17. What is lazy loading, and how does it improve performance?

For example, if you had a really long web page with a lot of images, then loading everything in at once slows things down.

Lazy loading only serves what is required in real-time, holding all else pending until we reach the part of the web page by scrolling down to it.

For images, lazy loading will load an image only when it is about to be seen, thus avoiding unnecessary bandwidth usage and time consumption.

Also read: Must-Try HTML and CSS Projects

18. Explain event delegation in JavaScript.

In JavaScript, we often need to handle clicks and other events on multiple elements. Instead of adding listeners to each one, we use event delegation.

This means you’re adding a single listener to a parent element that is looking for events on its child elements.

19. What is a callback function in JavaScript, and why are they used?

A callback function is a function passed as an argument to another function. Once the main function has finished, it “calls back” the callback.

Why use them?

They are appropriate for usage in scenarios such as manipulation of data after the document load, adding interactivity or events after some time has passed.

20. What are the differences between local storage, session storage, and cookies?

Local Storage: The information is stored with no end date, so when you close the browser, it persists.

Session Storage: Only available during the page’s session. Close the browser, and it’s all gone.

Cookies: Small data files stored with an expiry date. They’re often used for tracking sessions and are sent to the server with each request.

Comparison Table:

Advanced Topics: Tackling Complex Web Development Interview Questions

21. What is the difference between client-side and server-side rendering?

With client-side rendering (CSR), the browser does all the work.

JavaScript loads the initial content, and data gets pulled in as we interact. CSR works well for single-page apps where users stay on the page for a while.

Initial loading might be slow, especially on weaker devices.

Server-side rendering (SSR), on the other hand, has the server do the heavy lifting first.

HTML is generated on the server, so content loads faster initially, which is great for SEO. But with SSR, each page change needs a new server request, which can be slower for dynamic sites.

22. Explain JavaScript promises and how they differ from callbacks.

JavaScript promises and callbacks handle async tasks.

Callbacks are like inviting a friend over. Once they arrive, they knock, and you let them in—only then do things move forward.

Promises streamline this process.

Instead of waiting to “let in” the task, promises give us three options:

• Pending: The task is still running.
• Fulfilled: The task was completed successfully.
• Rejected: Something went wrong.

Promises help us avoid “callback hell,” making the code clearer.

23. Define web accessibility and give a few best practices to ensure web accessibility.

Web accessibility ensures people with and without disabilities can access the site. That’s not just about passing legal; it’s an issue of respect.

Consider that a person has a visual disability. He or she is not going to be able to read or navigate well.

Best Practices for Accessibility:

• Alt text for the images: Describe the image so screen readers can report it back to the user out loud.
• Keyboard navigation: Making sure every function would work on the site as well if a mouse did not exist.
• High contrast colours: To make it visible, especially in low lights.
• ARIA roles: Tags and navigation, which are readable by screen readers.

Accessibility is not about the checklist; it is about making a site really accessible.

24. What is HTTP/2, and how does it improve upon HTTP/1.1?

HTTP/2 is faster than the older HTTP/1.1.

Key improvements in HTTP/2:

• Multiplexing: Multiple requests occur at once over a single connection; HTTP/1.1 waits for one request to complete before starting the next.
• Header compression: Compresses HTTP headers, saving precious time and bandwidth.
• Server push: Pushes resources the browser will need ahead of time, like CSS and JavaScript files, even before it asks.

These changes make HTTP/2 reduce page load time dramatically on pages with many elements. Think of it as replacing a single-lane road with a freeway—more data, less waiting.

25. How do you manage security issues like Cross-Site Scripting (XSS) in web apps?

XSS (Cross-Site Scripting) is a very popular hacking method where malicious scripts are injected into trusted sites. Such scripts can steal data or manipulate content.

For stopping XSS:

• Escape user input: Filter input from forms, search bars, and comments.
• Content Security Policy (CSP): Limits what will and will not be allowed to load on your site.
• Sanitize data: This basically eliminates any risky character and also removes it.

26. Explain the concept of closures in JavaScript with an example.

Closures are like tiny memory banks. When a function is created inside another function, it remembers the surrounding scope—even if that outer function finishes running.

Closures keep variables alive even when the original context is gone.

27. What is a Content Delivery Network (CDN), and why is it used?

A Content Delivery Network (CDN) speeds up how fast content loads. With a CDN, content is stored in multiple locations worldwide.

When someone visits a site, they get the data from the server closest to them.

Benefits of a CDN:

• Reduced load times: By serving data from nearby locations.
• Better handling of traffic spikes: More servers handle the load better.
• Improved user experience: Faster load times mean happier users.

Think of it as setting up mini-servers around the globe for quick delivery.

28. How can CSS transitions be used to animate elements on a webpage?

CSS transitions bring movement to web elements. With transitions, we can make simple animations like fading in, changing colours, or moving objects.

They trigger when we hover, click, or focus on elements.

Transitions are a quick way to add polish to interactive elements.

29. What is the difference between the == and === operators in JavaScript?

When comparing in JavaScript, == and === behave differently.

The == operator only checks the value.

So, 5 == “5” returns true.

The === operator, however, checks both value and type, which makes it more accurate.

5 === “5” returns false

Use === when you want strict comparisons. It prevents unintended bugs by making sure both type and value match.

30. Explain Type Coercion in JavaScript and how to avoid errors.

Type coercion happens when JavaScript automatically converts data types. It can be helpful, but it can also cause unexpected issues.

To avoid this:

• Use Number() or String() to explicitly convert types.
• Stick to === for comparisons.

Also Read: Top 24 JavaScript Interview Questions 2024

Web Development Interview Questions to Check Technical Skills

31. What are web sockets? How do they achieve real-time communication?

Web sockets let users connect to a server and keep that connection open, allowing data to stream back and forth with ease without reloading the page.

Web sockets automatically update and load new information, even if the user doesn’t refresh the page. They’re perfect for apps like live chats, stock tickers or multiplayer games.

32. Explain HTTP status codes such as 200, 301, 404, and 500.

HTTP status codes can give us a hint at what is happening when we attempt to load a page.

• 200 (OK): Everything’s fine; it loaded the page.
• 301 (Moved Permanently): The page moved permanently to another URL, and the browser should be made to follow it.
• 404 (Not Found): The server could not find the page we tried to request.
• 500 (Internal Server Error): Something happened on the server.

Knowing these codes can help debug issues and improve user experience.

33. What is a single-page application (SPA), and how is it structured?

Single Page Applications provide a seamless user experience. Instead of loading multiple pages, the SPA loads one page and dynamically updates the content as we interact.

Facebook and Gmail are the best examples. They do not reload; they just update the needed parts.

This minimises the load time and makes it feel smoother.

SPA Structure:

• HTML Template: One single HTML file for a base
• JavaScript Framework: Libraries like React or Angular that update contents.
• API Calls: Fetches data from the server upon demand.

SPAs are highly dependent on JavaScript and, hence, are suitable for interactive fast sites as they make use of AJAX or Fetch to fetch new data.

34. What is a web server? Explain the function of a web server and how web hosting works.

A web server is a computer that contains files when you are surfing around to look at websites.

Web hosting is a service in which you lease space on these servers to upload websites, kind of like leasing space for your site on the Internet.

When we host a website, we upload files to a server that makes them available online.

Common Types of Web Hosting:

• Shared hosting: A single server is utilised by various sites, thus making it cost-effective.
• Dedicated hosting: One site will use an entire server, and therefore, its speed improves.
• Cloud hosting: Multiple servers’ resources are shared by a website, which makes it scalable.

Hosting is basically important for making any site live – whether it is a blog or e-commerce.

Also Read: 20 Best Frontend Technologies

35. Explain the difference between CSS class and ID selector.

A CSS class is a reusable style that we can apply to many different elements, whereas an ID selector is unique to just one element.

Use classes for common styles you’re going to apply in lots of places, like buttons or headings. IDs are one-off stylings, like a specific section.

36. What are pseudo-classes in CSS, and how do they enhance styling?

Pseudo-classes are based on an element’s state, such as hover or click. They are perfect for interactive elements where you can change colours, size, or background according to user actions.

Common Pseudo-Classes:

• hover: Whenever the user hovers over an element.
• focus: When an element is focused, just like when a form field has been clicked.
• nth-child(): Targets a certain number of children in a list or table.

37. How does the CSS box model work? Describe its components.

The CSS box model is the way elements are constructed on a webpage. Becoming proficient in the box model helps one to really hone layout and spacing.

Every element in CSS is a box, and that box contains:

• Content: The main area, like text or images.
• Padding: This is the space between the content and the border.
• Border: This is the line around the element.
• Margin: This is the space outside the border, separating the element from other elements.

Box Model Example Table:

38. Explain what version control is and how Git is used in web development.

Version control tracks changes over time in code. The tool which helps us do it is called Git.

It is really like saving a version for each of your projects such that if anything breaks then you can always roll it back to the working copy. In web development, Git is so important during teamwork. It keeps track of who changed what and makes collaboration smooth.

Git Commands to Know:

• git init: Starts tracking a new project.
• git add: Adds changes to the next commit.
• git commit -m “message”: Saves the changes with a message.
• git push: Sends changes to the central repository.

Git simplifies project management and ensures everyone on the team stays in sync.

39. Explain Content Security Policy (CSP) in web development.?

Content Security Policy, or CSP, is like having a security guard watch your website. It just tells the server which files are permitted to load within your site and will block everything that is not part of it.

But this especially guards against cross-site scripting, or XSS attacks, in which malicious scripts are injected into web pages by the attacker.

40. What are RESTful services, and what are CRUD operations?

RESTful services are a standard way of structuring APIs. It allows connecting frontend apps with a server using standard HTTP methods.

CRUD operations (Create, Read, Update, Delete) are the main actions we do with REST APIs.

Think of CRUD as the building blocks for web apps:

• Create (POST): Adds new data.
• Read (GET): Retrieves data.
• Update (PUT): Changes existing data.
• Delete (DELETE): Removes data.

Framework and Library-Specific Web Development Interview Questions

41. What is a Virtual DOM in React, and what is it all about?

The Virtual DOM is a lightweight copy of the actual DOM (Document Object Model) that React keeps in memory.

When something changes on a page, such as a button click or form update, React updates the Virtual DOM first. Then, it compares the updated Virtual DOM with the real DOM and only updates what changed. This is called reconciliation.

Instead of reloading the whole page, React checks for differences and can update faster.

42. Describe the two-way data binding of Angular and its benefits.

Two-way binding will maintain synchronous data between the model and view.

In Angular, if you update a form input, it immediately updates the component’s state. And if the component’s state changes, the view updates right away too.

This is a big help for building interactive forms or live-updating content.

Advantages of Two-Way Data Binding:

• Live updates: Changes appear instantly, creating a smooth user experience.
• Simplified code: Less boilerplate code to keep data in sync.
• Ideal for forms: Helps create responsive forms without extra logic.

43. What are the key features of Vue.js?

Vue.js is a popular JavaScript framework known for its simplicity and flexibility. It combines the best parts of React and Angular with its own twist.

Key Features of Vue.js:

• Reactive data binding: Just like Angular, but easier to set up.
• Component-based: Like React, it uses reusable components for building UIs.
• Directives: Special attributes like v-if and v-for simplify conditionals and loops.

44. What is a higher-order component (HOC) in React, and when is it used?

A higher-order component can be described as a wrapper function for components because it takes a component and returns the new component with a few extra features added in.

HOCs help us reuse component logic without repeating code.

This is especially useful for common tasks like authentication, permissions, or handling form input.

45. Explain the concept of state management and the use of Redux.

State management handles how data changes in an app over time. In React, we use Redux to centralise this data.

Redux stores all data in a single store, which every component can access. This avoids the “prop-drilling” problem, where data has to pass through multiple components.

Redux may take time to learn, but it simplifies complex apps by managing data predictably.

Also Read: Top 10 Most Popular Web Development Frameworks in 2024

46. What are Angular services, and how are they used within the framework?

Angular services are functions or objects that perform specific tasks. They’re like helpers that handle business logic or fetch data from an API.

Services make code reusable and organised. Instead of duplicating code in multiple components, we create a service once and use it everywhere.

47. Describe the purpose of props and state in React components.

In React, props and states control how components display and change data.

Props are inputs from a parent component. They’re read-only, so they don’t change within the component itself.

The state is internal data that changes over time. It’s perfect for tracking data like form input, button clicks, or loading status.

Props help pass data in while the state tracks internal changes.

48. How does dependency injection work in Angular?

Dependency Injection is the way through which Angular provides its components with all necessary services.

In Angular, besides instantiating directly, the injector provides components with the right service. This, in turn, makes it easier to swap out services for testing and keeps code loosely coupled.

49. What is the difference between synchronous and asynchronous data binding?

In JavaScript, binding could be either synchronous or asynchronous.

Synchronous simply means updates happen instantly; asynchronous implies updating data over time.

Angular uses synchronous data binding by default. However, for async data, for example, API calls, we make use of the async pipes or Observables to deal with the delayed updates.

50. Explain the use of hooks in React, especially useState and useEffect.

React hooks let us add state and lifecycle features to functional components.

Two main hooks are useState and useEffect.

• useState: Manages internal component data.
• useEffect: Runs side effects like data fetching or subscriptions.

Conclusion

This blog covers basic web development interview questions that range from front-end knowledge to back-end knowledge.

We have covered all of it, from a basic understanding of HTML, CSS, and JavaScript to the most crucial skills required to build dynamic, user-friendly interfaces, by discussing the frameworks React, Angular, and Vue. At the back end, we covered RESTful services and CRUD operations, which are crucial for data and functionality management in modern applications. We also discussed critical topics such as Virtual DOM and dependency injection that guarantee efficiency and maintainability.

Prepared with all these, one would be rounded up, thus capable of passing up any interview about web development.

Stay informed, stay prepared, and consider enrolling in Hero Vired’s Certificate Program in Full Stack Development with Specialisation for Web and Mobile to elevate your skills and career in the ever-evolving field of web development.