Web developers are in great demand and are expected to become much more so in the years to come. Strong job growth, the increase of e-commerce, the mobile-first world, developing technologies, and digital transformation are some of the factors that are fueling this demand. This is a thorough list of 40 web developer interview questions and answers to help you be ready for your next interview. Get started with our web developer course syllabus.
Web Development Interview Questions for Freshers
Here are the basic web developer interview questions and answers for freshers:
1. What is the purpose of the DOCTYPE declaration in HTML?
The HTML version is specified by the DOCTYPE declaration, which also guarantees that the browser presents the page in standards mode. It’s just <!DOCTYPE html> for HTML5.
The HTML document’s version and type are specified by the doctype declaration, which helps in proper document parsing by browsers. It is important because of backward compatibility, standards compliance, cross-browser consistency, and unpredictable rendering.
2. What is the box model in CSS?
One technique to specify the structure of HTML components on a webpage is to use the CSS box model. This idea is essential to web development. Content, padding, border, and margin make up the box model. It specifies the arrangement and spacing of the elements.
3. What are CSS preprocessors, and why use them?
CSS preprocessors are programming languages that enhance CSS’s built-in functionality.
By enabling the usage of variables, nesting, and functions, CSS preprocessors such as SASS or LESS improve the maintainability and scalability of CSS.
4. What is CSS specificity, and how is it calculated?
The algorithm that browsers employ to identify the CSS declaration that is most pertinent to an element, and, consequently, the property value that should be applied to the element, is known as specificity.
When more than one CSS rule matches an element, specificity decides which rule is used. The number of IDs, classes, and elements in the selector.
Example: #id >.class > element is used to calculate it.
5. What are props and states in React?
JavaScript objects called props and state are used in React to manage data inside components. These are essential ideas for creating user interfaces that are interactive.
Props: Data passed from a parent component that cannot be changed.
State: Modifiable information controlled by a component.
6. What is REST, and how does it work?
An architectural technique for creating networked applications is called REST (Representational State Transfer). It carries out CRUD tasks using the HTTP methods GET, POST, PUT, and DELETE.
It offers a set of guidelines for how clients and servers should communicate over the internet, encouraging scalability and flexibility in the development of web applications.
7. What is GraphQL?
GraphQL is an API query language that minimizes over-fetching and under-fetching by enabling clients to request only the data they require.
Developers can use GraphQL as an alternative to REST to create queries to retrieve data from several data sources with a single API call.
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8. What is progressive enhancement?
In order to provide a richer experience for those who can handle it, progressive enhancement is a web design technique where a website is first constructed with basic functionality and content that is accessible to all users, regardless of their browser capabilities.
Later, more sophisticated features and interactions are added only for users with modern browsers and faster internet connections.
9. What is event delegation?
A JavaScript technique called event delegation affixes a single event listener to a parent element rather than several child elements. To manage events at a higher level in the DOM tree, this method makes use of event bubbling.
10. What is CORS, and how do you handle it?
Web applications can access resources on various domains thanks to a security standard called Cross-Origin Resource Sharing (CORS). This technique overrides the same-origin policy (SOP) and is based on HTTP headers.
Cross-origin requests are restricted by CORS (Cross-Origin Resource Sharing). Setting the proper server headers (such as Access-Control-Allow-Origin) will take care of it.
11. What is closure in JavaScript?
A closure is a function that, even when run outside of its lexical scope, maintains access to it. In JavaScript, a closure is a function that retains access to the variables of its outer function even after the outer function has completed running. When a function is defined inside another function, closures are produced.
12. What is the difference between server-side rendering (SSR) and client-side rendering (CSR)?
SSR allows users to view content more quickly since the server creates all of the HTML content for each page and transmits it to the browser. In CSR, a minimum HTML file is sent to the browser, and JavaScript is used to dynamically render content.
- SSR: The client receives HTML that has been created on the server.
- CSR: JavaScript is used in the browser to build HTML.
13. What is responsive web design?
A website can automatically adjust to the screen size of the device it is being viewed on thanks to a technique called responsive web design (RWD). Making a website that functions and looks good on all devices is the aim. It makes use of media queries, scalable pictures, and flexible layouts to guarantee that a website adjusts to various screen sizes and devices.
14. What are semantic HTML elements?
HTML tags that explicitly state the meaning of the text they contain are known as semantic HTML elements. This aids in improving the readability, accessibility, and search engine optimization of online pages.
Content is given meaning by semantic elements like <header>, <footer>, <article>, and <section>, which also make the structure easier for screen readers and search engines to comprehend.
15. What is the difference between == and === in JavaScript?
While === checks for both value and type equality, === checks for value equality with type coercion.
16. What is two-way data binding in Angular?
Angular’s two-way data binding enables data to move both ways between the component and the view. Users can now engage with the data that is shown on the screen due to this.
By synchronizing the model and the view, two-way data binding ensures that modifications to one are mirrored in the other (e.g., [(ngModel)]).
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17. What is the virtual DOM in React?
A JavaScript version of the user interface (UI) stored in memory is called the virtual DOM (VDOM) in React. This version of the Document Object Model (DOM) is lightweight. Performance is enhanced and updates are optimized with the help of the virtual DOM.
18. How do you optimize a website for SEO using HTML?
The following are the important ways to optimize a website for search engines:
- Descriptive title tags.
- Relevant meta descriptions.
- Appropriate header tags (H1, H2, H3).
- Descriptive alt text for images.
- Well-structured URLs.
- Internal linking with pertinent anchor text.
- Canonical tags for duplicate content
- Clean and valid HTML code.
19. What is the event loop in JavaScript?
One part of the JavaScript engine that controls code execution is the event loop, which also gathers and processes events and runs queued subtasks. It makes advantage of task queues and background Web APIs to make JavaScript single-threaded and non-blocking.
By continuously monitoring the call stack and completing jobs in the callback queue, the event loop is a technique that manages asynchronous operations.
20. What is a CDN, and why use it?
A content delivery network, or CDN, is a system of computers that improves load times and lowers latency by delivering material to consumers based on their location. It brings the content closer to the user’s location, improving the user experience.
By reducing the distance that data must travel to reach the user, a CDN (Content Delivery Network) is a geographically dispersed network of servers that keeps copies of website content, such as images, videos, and HTML pages, closer to users worldwide.
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Web Developer Interview Questions for Experienced
Here are the advanced-level web developer interview questions and answers for experienced.
21. What is the difference between <div> and <span>?
The primary distinction between a span and a div in HTML is that the <div> is an inline element and the <spin> is a block-level element. Accordingly, spans group and style text or inline elements, whereas divs establish sections or divisions in a document.
| Factor | <div> | <span> |
| Function | It makes a document’s sections or divisions. | Styles and groups either inline components or text. |
| Uses | It wraps a sizable portion of material for styling or layout. | It targets or styles particular textual elements. |
| Components | Additional components, including paragraphs, headings, photos, links, and even other divs. | Additional inline components, such text, pictures, links, or other spans. |
22. What is the purpose of the alt attribute in an image tag?
In addition to improving accessibility for screen readers, the alt element offers alternate text for an image in the event that it does not load.
Alternative text for an image that cannot be displayed is specified via the alt property in an image tag. Screen readers and browsers use this text to explain the image.
- Accessibility: Assists those who are blind or visually handicapped in comprehending the meaning of images.
- Search Engine Optimization: In order for an image to appear in pertinent search results, search engine optimization helps search engines comprehend what the image is about.
- User-Friendliness: Increases the accessibility and usability of pictures.
23. What is the difference between margin and padding?
Padding is the area inside an element between the border and the content, whereas margin is the area outside an element.
| Factors | Padding | Margin |
| Definition | The space between the border and the content of an element. | The space between one element’s border to the subsequent element. |
| Function | Makes room inside an element. | Make room between components. |
| Use Cases | Enhances an element’s aesthetic appeal and readability. | It keeps text and images apart. |
24. What is the difference between inline, block, and inline-block?
Inline: Elements (like <span>) flow in a line.
block: Elements begin on a new line (e.g., <div>) and take up the entire width.
Inline-block: Buttons and other elements that flow in a line can also have width and height.
The following are the differences between inline, block, and inline-block:
| inline | block | inline-block |
| Cannot set width or height. | Can set width and height. | Can set width and height. |
| Flows naturally within a line. | Starts on a new line. | Flows inline with other elements. |
| Examples: <span>, <a> | Examples: <p>, <div> | Useful for elements that need to sit next to each other but have specific dimensions (like buttons in a horizontal menu). |
25. What is the difference between let, const, and var?
The JavaScript variables “let”, “const”, and “var” are all declared using these keywords; however, their scope and reassignment capabilities vary:
- var: Variables defined with the symbol “var” are accessible throughout the entire function in which they are declared and may be redeclared or reassigned within that scope. Because of possible scoping problems, they are regarded as outdated.
- let: Variables declared with “let” are exclusively available within the block in which they are declared; they can be reassigned but not redeclared within that block. This is known as block-scope.
- const: Contrary to “let,” variables defined with “const” cannot be reassigned after initialization, thereby rendering them read-only constants. Const also has a block-scope.
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26. What is the purpose of async and await in JavaScript?
When writing asynchronous code in JavaScript, the keywords “async” and “await” are used to make it more readable and sequential.
They allow a function to “wait” for a promise to resolve before continuing with its execution, making it look like synchronous code even when handling time-consuming operations, such as network requests, without causing the main thread to stall. “Async” designates a function as asynchronous, while “await” pauses its execution until a promised value is available.
Async keyword: A function that is declared as “async” automatically returns a promise, allowing you to use “await” inside of it to halt execution until the completion of another asynchronous operation.
Await keyword: When used in an “async” function, “await” is positioned before a promise-based operation, causing the function to pause execution until the promise has been resolved.
27. What is the difference between React and Angular?
While Angular is a complete framework with integrated capabilities like dependency injection and routing, React is a library that focuses on the view layer. Although they are both well-liked JavaScript frameworks for creating online apps, React and Angular are not the same.
| Factor | React | Angular |
| Type | JavaScript library. | Front-end framework. |
| Data Binding | One-way. | Two-way. |
| Performance | Faster and smaller bundle size. | Slower and larger bundle size. |
| DOM | Virtual DOM. | Real DOM. |
| Architecture | Component-based. | Opinionated structure. |
| Suitability | Suitable for smaller projects. | Suitable for large-scale applications. |
28. What is Vue.js, and how does it compare to React?
With a simplified syntax and built-in features like directives, Vue.js is a progressive JavaScript framework that is simpler to include into applications than React.
React is a JavaScript library that offers more flexibility and is well-known for its JSX syntax, which blends HTML-like structures directly into JavaScript code.
Both frameworks use a virtual DOM for efficient updates, but Vue.js is a progressive JavaScript framework for creating user interfaces that is frequently thought of as more beginner-friendly than React because of its simpler syntax and reliance on standard HTML templates.
29. What is the difference between GET and POST requests?
When retrieving data, we can use GET; when submitting data, we can use POST. POST is used for more complicated tasks like uploading a file or submitting a form, whereas GET is frequently used for simpler data retrieval, such as retrieving a web page. An all-in-one API tool is Apidog.
GET: Makes a request for data from a server; the URL displays the data.
POST: Creates or updates a resource by sending data to a server; the data is not displayed in the URL.
30. What is JWT, and how is it used?
A small, URL-safe token called JWT (JSON Web Token) is used to safely send data as a JSON object between parties. It is a method of using JSON to safely exchange data between a client and a server. Web applications and APIs use JWTs for authorization and authentication.
How JWT is used:
- The user gives the server their login information so it may be validated.
- A JWT with user and session information is generated by the server.
- A secret key that only the server knows is used to digitally sign the JWT.
- The client receives the JWT.
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31. What is the difference between HTTP and HTTPS?
HTTP is a protocol that enables a browser to request resources from a server, while HTTPS is a secure variant of HTTP that encrypts data. The major differences between them are as follows:
| Factor | HTTP | HTTPS |
| Security | It sends data in plain text. | It uses the SSL/TLS protocols to encrypt data. |
| Purpose | Usually utilized for casual browsing. | Preferred for private data, such as passwords. |
| URL | Begins with “http://” | Begins with “https://” |
| Port | It operates by default over port 80. | It uses port 443 for operation. |
| Server Verification | It doesn’t confirm the identification of the server. | It uses cryptographic certificates to confirm the identity of the server. |
32. What is the difference between cookies, sessionStorage, and localStorage?
The major difference between Cookies, sessionStorage, and localStorage are:
| Cookies | sessionStorage | localStorage |
| Small data stored in the browser, sent with every request. | Data stored for the duration of a session. | Data stored persistently until manually cleared. |
| Accessible from any window. | Accessible from the same tab. | Accessible from any window. |
| Expiration is manually set. | On tab close. | Never expire. |
| Can be stored browser and server. | Server storage only. | Server storage only. |
33. What is Webpack, and why use it?
A module bundler called Webpack gathers CSS, JavaScript modules, and other resources into a production-ready bundle. This program, which bundles JavaScript apps into static assets, is open-source and free. It is intended to enhance load times and performance.
Uses of Webpack:
- Manage Dependencies: Every file and its dependencies are compiled into a dependency graph by Webpack. This enables developers to create web applications using a modular architecture.
- Bundle Assets: Webpack creates one or more bundles that contain all the modules your project needs. Your index.html file can make reference to these packages.
- Transform Assets: Front-end assets like HTML, CSS, and pictures can be changed with Webpack.
- Improve Performance: Webpack is made to speed up load times and performance.
34. What is the purpose of service workers?
Service workers allow Progressive Web Apps (PWAs) to cache, sync in the background, and operate offline. It gives developers control over how a website behaves when accessing network resources, including serving cached content when offline.
It does this by acting as a proxy between a web browser and web servers, allowing developers to intercept network requests and manage how resources are loaded, primarily to enable offline functionality by caching assets and provide a better user experience even when internet connectivity is poor.
35. What is the difference between null and undefined in JavaScript?
Null and undefined are two separate types in JavaScript that stand for different values. Null is an assignment value, which indicates that a variable has been declared and given the value of null, whereas undefined, by definition, indicates that a variable has been declared but has not yet been assigned a value.
- null: Indicates a purposeful lack of value.
- Undefined: Denotes a declared variable without a value given to it.
36. How do you debug a web application?
Make use of breakpoints, console logs, browser developer tools, and programs like the VS Code debugger or Chrome DevTools. We can use these tools to identify the problematic code section and fix it. The main method for debugging a web application is to use the developer tools in your browser to,
- Examine the code.
- Set breakpoints.
- Check network requests.
- Examine console logs.
- Determine the cause of errors by looking at variables and their values at various points in the application flow.
37. How do you optimize website performance?
The ultimate goal is to decrease loading times and enhance user experience. Reduce the number of HTTP requests, minify CSS and JS files, employ lazy loading, compress pictures, and enable caching.
Various ways to improve website performance:
- Compressing images.
- Minimizing HTTP requests.
- Turning on browser caching.
- Using a Content Delivery Network (CDN).
- Minifying code.
- Minimizing redirects.
- Optimizing third-party scripts.
- Tracking performance with tools like Google PageSpeed Insights to pinpoint areas for improvement.
38. What is your experience with version control systems like Git?
Talk about how you’ve used Git procedures like feature branching and commands like clone, commit, push, pull, branch, and merge.
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39. How do you handle cross-browser compatibility issues?
Write code that works across browsers, leverage tools like BrowserStack, and use polyfills for functionality that aren’t supported. This frequently entails employing strategies like CSS resets, normalization, and progressive enhancement.
Developers should prioritize writing clean, web-standard code, use CSS frameworks like Bootstrap, test extensively across browsers, and make any necessary code and style changes to ensure consistent functionality across platforms.
40. Describe a challenging project you worked on and how you solved it.
Provide a specific example, highlighting your problem-solving skills, collaboration, and the outcome.
Sample Answer: Creating a new software application from the ground up for a customer in a highly regulated industry was one of the most difficult projects I worked on. This wouldn’t be an issue normally, but the client had tight deadlines and a limited budget.
Conclusion
It’s important to thoroughly understand the technical and non-technical facets of the position in order to prepare for a web developer interview. Preparing with these top 40 web developer interview questions and answers can help you show off your proficiency in areas like front-end and back-end development, and problem-solving. Master in web development with our web developer training in Chennai.
