Front-End Developer Interview Questions and Answers for 2025

This question tests your understanding of the core technology behind structuring web pages.

HTML stands for HyperText Markup Language. It is the traditional language used to create the structure of web pages. HTML uses elements, which consist of tags, to organise content like text, images, and links into a readable and functional layout.

This question intends to evaluate your knowledge of how HTML operates.

Here's how you can answer this question:

Tags are the building blocks of HTML and are employed to define elements on a web page. They are enclosed within angle brackets, for example,

Tags often come in pairs, like

This question is asked to assess your understanding of modern HTML practices. Here ‘s how you can answer it:

“Semantic elements clearly define their meaning in the content context, making the HTML more readable and accessible.

Examples include

They improve SEO and make it easier for developers and browsers to interpret the page structure.”

This question aims to determine your understanding of designing for users.

User-centered design is a process where the end user's needs, preferences, and limitations are prioritised throughout development. This process assures that the final product is intuitive, efficient, and satisfying.

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Here, the intent is to test your technical knowledge of HTML structure.

Here's how you can answer this question:

Empty elements do not have closing tags and cannot contain any content. Examples include

These elements serve specific purposes, like adding a line break or embedding an image.

This question intends to assess your understanding of modern HTML enhancements.

Here's how you can answer this question:

HTML5 introduced features like semantic elements, multimedia support with

This is used for graphics, offline capabilities with local storage, and improved APIs for enhanced interactivity and functionality.

This question tests your ability to write basic HTML.

The primary structure of an HTML document includes:

This defines the document type and includes a head section for metadata and a body section for content.

This question aims to gauge your knowledge of web performance and scalability.

Load Balancing allocates network or application traffic across multiple servers, ensuring reliability and performance. It prevents any single server from being overwhelmed by traffic.

This question assesses your familiarity with tools used in Front-End Development. npm stands for Node Package Manager.

It is a package manager for JavaScript that allows developers to install, share, and manage dependencies for their projects.

This question aims to check your understanding of the core scripting language used in web development.

JavaScript is an interpreted programming language that enables interactivity and dynamic web content. It is commonly used for tasks like form validation, animations, and creating single-page applications.

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This question tests your understanding of variable visibility in code.

Scope in JavaScript determines the accessibility of variables. There are three types:

a) Global Scope: Variables declared outside any function are accessible everywhere.

b) Function Scope: Variables declared inside a function are accessible only within that function.

c) Block Scope: Variables declared with let or const within a block ({}) are limited to that block.

This question assesses your understanding of asynchronous programming challenges.

Callback hell is where nested callbacks make code difficult to read and maintain. It occurs when multiple asynchronous operations are dependent on one another. Using promises or async/await helps mitigate this issue.

This question tests your knowledge of web security practices.

CSP is a browser feature that helps prevent cross-site scripting (XSS) attacks by allowing developers to specify the sources from which content is loaded. It is implemented using the Content-Security-Policy HTTP header.

This question evaluates your knowledge of common web vulnerabilities.

XSS is a security vulnerability where an attacker infiltrates malicious scripts into web pages viewed by others. It can be mitigated by sanitising user inputs, escaping outputs, and implementing CSP.

This question is asked to assess your knowledge of object-oriented programming concepts.

Polymorphism is the ability of a single function, method, or object to behave differently based on the context. In JavaScript, it is often used with method overriding or prototypes.

This question evaluates your knowledge of coding standards and debugging.

Strict Mode is a component in JavaScript that enforces stricter parsing and error handling. It prevents the use of undeclared variables and disallows specific syntax. You enable it by adding "use strict"; at the beginning of a script or function.

This question tests your understanding of software design principles.

SOLID stands for five principles of object-oriented design:

S: Single Responsibility Principle

O: Open/Closed Principle

L: Liskov Substitution Principle

I: Interface Segregation Principle

D: Dependency Inversion Principle

These principles help create maintainable and scalable code.

This question aims to assess your understanding of JavaScript functions.

Here's how you can answer this question:

An IIFE is a JavaScript function executed immediately after being defined. It helps create a private scope and avoid polluting the global namespace.

Example:

This question evaluates your understanding of reusable code structures.

A mixin is a reusable code that can be added to objects or classes to extend their functionality without using inheritance. In JavaScript, this is often achieved by copying properties from one object to another.

This question aims to check your knowledge of styling web pages.

CSS stands for Cascading Style Sheets. It is used to style HTML elements, including layouts, colours, fonts, and spacing, to enhance the visual appearance of web pages.

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This question tests your understanding of targeting elements for styling.

CSS selectors are patterns utilised to select HTML elements for styling. Examples include:

Type Selector: h1

Class Selector: .className

ID Selector: #idName

Attribute Selector: [type="text"]

Pseudo-classes: :hover

This question evaluates your knowledge of responsive design.

Here's how you can answer this question:

Media queries apply styles based on device properties like screen width or orientation.

Example:

This question intends to test your understanding of how elements are rendered.

The CSS box model describes the rectangular layout of an element, consisting of:

a) Content: The content inside the element.

b) Padding: Space between content and the border.

c) Border: The edge surrounding the padding.

d) Margin: Space between the component and others.

This question intends to evaluate your understanding of CSS specificity.

The !important rule overrides any other styles, regardless of specificity. In rare cases, it is used to enforce a style but should be avoided as it reduces maintainability.

This question intends to understand your self-assessment of skills.

A Front-End Developer needs strong skills in HTML, CSS, JavaScript, responsive design, version control (e.g., Git), and frameworks like React or Angular. Communication and problem-solving abilities are also crucial.

This Question assesses your knowledge of performance optimisation.

a) Minify CSS, JavaScript, and images.

b) Use lazy loading for images and videos.

c) Implement caching and a Content Delivery Network (CDN).

This question evaluates your understanding of inheritance models.

a) Class Inheritance: Mimics traditional OOP with class and extends.

b) Prototypal Inheritance: Objects inherit directly from other objects using prototypes, allowing for more dynamic behaviour.

This question aims to test your knowledge of JSON operations.

JSON.stringify() converts a JavaScript object or array into a JSON string, making it suitable for storage or transmission.

This question assesses your knowledge of responsive images.

The srcset attribute allows browsers to choose the most appropriate image file based on device resolution and size, improving performance and user experience.

This question tests your understanding of databases.

MySQL is an Open-source Relational Database Management System (RDBMS) that uses structured query language (SQL) to store, retrieve, and manage data.

This question tries to assess your knowledge of NoSQL databases.

MongoDB is a NoSQL database that stocks data in flexible, JSON-like documents. It is ideal for handling large-scale, unstructured data.

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This question evaluates your knowledge of source code management.

A VCS tracks changes to code over time, allowing developers to collaborate, revert to previous versions, and manage codebases. Examples include Git and SVN.

This question tests your knowledge of Git workflows.

Git Stash temporarily saves changes that are not yet ready to commit, allowing you to switch branches or work on other tasks without losing progress.

This question tries to understand your approach to handling branches.

Merge: Combines two branches while preserving their history.

Rebase: Reapplies commits from one branch to another, creating a linear history.

This question tries to evaluate your understanding of object-oriented programming.

Prototypes enable inheritance and allow objects to share properties and methods, reducing memory usage and improving efficiency.

This question tries to test your understanding of asynchronous programming.

The event loop is an instrument that handles asynchronous operations by continuously checking the call stack and task queue, ensuring non-blocking execution.

This question tries to assess your understanding of script loading optimisation.

a)defer: Loads the script in the background and executes it after parsing the HTML.

b)async: Loads and executes the script independently of the HTML parsing.

This question tries to test your knowledge of data types.

a) Undefined: A variable is stated but not assigned a value.

b) Undeclared: A variable that hasn’t been stated.

c) Null: Represents an intentional absence of a value.

This question tries to evaluate your problem-solving skills.

Use a Set:

This question tries to test your understanding of compilation strategies.

a) AoT: Compiles code at build time, improving performance.

b) JiT: Compiles code at runtime, offering flexibility but with slower initial performance.