20+ Senior Web Developer Interview Questions and Answers

Designing a scalable invoicing system for SMEs with considerations for database schema, API design, and performance optimization.

• Database schema should include tables for invoices, customers, products/services, and payments with proper relationships and indexing for efficient querying.

• API design should follow RESTful principles with endpoints for creating, updating, and retrieving invoices, customers, and products/services.

• Performance optimization can be achieved through cach...read more

Implement shopping cart functionality in JavaScript for an e-commerce website.

• Create an array to store the items in the cart

• Implement functions to add, remove, and update quantities of items

• Calculate the total price by iterating through the items in the cart and summing up the prices

I would design a component library by following a systematic approach to ensure usability and robustness.

• Conduct thorough research on the project requirements and user needs

• Create a design system with reusable components that follow best practices and design principles

• Implement accessibility features to ensure all users can interact with the components

• Test the components extensively for functionality, performance, and compatibility

• Document the component library with clear gui...read more

PHP is a server-side scripting language used for web development. It is case-sensitive due to its origins in C programming.

• PHP stands for Hypertext Preprocessor and is commonly used for creating dynamic web pages.

• PHP is case-sensitive, meaning variables, functions, and classes must be referenced with the exact casing.

• This case-sensitivity is inherited from its roots in the C programming language.

• For example, $variable and $Variable would be treated as two different variables ...read more

The CSS box model is a design concept that defines the structure and layout of elements on a webpage.

• The box model consists of content, padding, border, and margin around an element.

• Content area is where text and images are displayed.

• Padding is the space between the content and the border.

• Border is the line that goes around the padding.

• Margin is the space outside the border, separating the element from other elements.

• The box model affects layout by determining the size and sp...read more

My current CTC is $80,000 and my expected CTC is $90,000.

• Current CTC: $80,000

• Expected CTC: $90,000

Microservices can be connected through APIs, message queues, or service mesh.

• Use APIs to allow microservices to communicate with each other over HTTP or other protocols.

• Implement message queues like RabbitMQ or Kafka for asynchronous communication between microservices.

• Utilize service mesh tools like Istio or Linkerd to manage communication, security, and monitoring between microservices.

Doctype in HTML specifies the version of HTML being used and helps browsers render web pages correctly.

• Specifies the version of HTML being used

• Helps browsers render web pages correctly

• Prevents browsers from entering quirks mode

Use React's state and map function to reverse DOM tree elements without duplicating code

• Use React's state to store the original DOM tree elements

• Use the map function to render the elements in reverse order

• Update the state with the reversed elements to reflect the changes in the DOM

I would design a complete website based on the provided reference website.

• Analyze the reference website for layout, color scheme, navigation, and functionality

• Create wireframes and mockups based on the reference website

• Implement responsive design for mobile and desktop users

• Test the website for usability and functionality

• Optimize the website for performance and SEO

Use sliding window approach to find longest substring with no repeating characters.

• Use a set to keep track of characters in the current substring

• Use two pointers to create a sliding window

• Update the pointers and set as you iterate through the string

Dynamic websites have content that can change based on user input or interactions, while static websites display the same content to all users.

• Dynamic websites use server-side scripting languages like PHP, ASP, or JSP to generate content on the fly.

• Static websites are built using HTML and CSS and the content remains the same for all users.

• Examples of dynamic websites include social media platforms like Facebook or e-commerce sites like Amazon.

• Examples of static websites inclu...read more

A bug is a flaw or error in a computer program that causes it to behave unexpectedly or crash.

• Bugs can cause software to malfunction or crash

• They can be caused by coding errors, hardware issues, or external factors

• Debugging is the process of identifying and fixing bugs

• Examples of bugs include syntax errors, logic errors, and race conditions

Variables can be changed during program execution, while constants remain constant.

• Variables can be reassigned with different values, while constants have a fixed value.

• Variables are declared using 'var', 'let', or 'const' keywords, while constants are declared using 'const' keyword.

• Constants are typically used for values that should not change throughout the program, like mathematical constants or configuration settings.

React is just a library because it focuses on the view layer of the application and can be used with other libraries or frameworks.

• React is a JavaScript library for building user interfaces.

• It focuses on the view layer of the application, allowing developers to create reusable UI components.

• React can be used with other libraries or frameworks, such as Redux for state management or React Router for routing.

• Unlike frameworks like Angular, React does not provide features for han...read more

Using JavaScript to add functionality to a web page design

• Use event listeners to trigger actions based on user interactions

• Manipulate the DOM to update content dynamically

• Utilize AJAX to fetch data from a server without refreshing the page

Inheritance is a concept in object-oriented programming where a class inherits properties and behaviors from another class.

• Inheritance allows for code reusability and promotes a hierarchical relationship between classes.

• Types of inheritance include single inheritance (one class inherits from one parent class), multiple inheritance (one class inherits from multiple parent classes), and multilevel inheritance (one class inherits from a parent class, which in turn inherits from ...read more

Oops concepts refer to Object-Oriented Programming concepts which include inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation involves bundling data and methods that operate on the data into a single unit.

• Polymorphism allows objects to be treated as instances of their parent class.

• Abstraction involves hiding the complex implementation details and showing only the necessary fea...read more

Polymorphism is the ability of a function or method to behave differently based on the object it is acting upon.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• It enables a single interface to represent a group of related interfaces.

• Examples include method overloading and method overriding in object-oriented programming.

The main part of hacking is gaining unauthorized access to a system or network.

• Hacking involves exploiting vulnerabilities in software or hardware

• It can be used for malicious purposes such as stealing data or disrupting services

• Ethical hacking is a legitimate practice used to identify and fix security weaknesses

• Examples of hacking techniques include phishing, SQL injection, and social engineering

Two common hooks in React are useState and useEffect.

• useState: Used to add state to functional components.

• useEffect: Used to perform side effects in functional components.

Microservices are a software development technique where applications are composed of small, independent services that communicate with each other through APIs.

• Microservices break down a large application into smaller, manageable services

• Each service is responsible for a specific function and can be developed, deployed, and scaled independently

• Communication between services is typically done through lightweight protocols like HTTP or messaging queues

• Microservices promote flex...read more

React is a JavaScript library for building user interfaces.

• React allows developers to create reusable UI components.

• It uses a virtual DOM for efficient rendering.

• React is often used in conjunction with other libraries like Redux for state management.

• React was developed by Facebook and is maintained by a community of developers.

Traits are reusable code blocks that can be mixed into classes, while interfaces define a contract that a class must follow.

• Traits can be used to add methods to a class without inheritance

• Interfaces define a set of methods that a class must implement

• A class can implement multiple interfaces, but can only inherit from one class

• Traits promote code reusability and reduce code duplication

A filter code is used to sort and display specific data based on certain criteria.

• Filter codes can be used in programming languages like JavaScript to manipulate arrays or objects.

• Examples include using filter() method in JavaScript to filter out elements from an array based on a condition.

• Filter codes can also be used in SQL queries to retrieve specific data from a database.