AppsInvo React Js Frontend Developer Interview Questions and Answers

Q1. What are oops concepts in java, explain real time scenario
Ans. 
OOPs concepts in Java include inheritance, polymorphism, encapsulation, and abstraction.
• Inheritance allows a subclass to inherit properties and methods from a superclass.

• Polymorphism allows objects to take on multiple forms and behave differently based on their context.

• Encapsulation hides the implementation details of an object and only exposes necessary information.

• Abstraction allows for the creation of abstract class...read more
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Q2. Uses of interface, inheritance
Ans. 
Interfaces define contracts for behavior, while inheritance allows for code reuse and polymorphism.
• Interfaces allow for loose coupling and abstraction, enabling multiple implementations of the same behavior.

• Inheritance allows for code reuse and extension of existing classes, reducing code duplication.

• Polymorphism allows objects of different classes to be treated as if they were of the same class, simplifying code and i
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Q3. SQL query for join of tables
Ans. 
SQL query for joining tables
• Use JOIN keyword to combine two or more tables based on a related column

• Specify the columns to be selected using SELECT keyword

• Use ON keyword to specify the condition for joining the tables

• Different types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN
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Q4. Java concepts used in your project
Ans. 
Used Java concepts such as inheritance, polymorphism, and exception handling in my project.
• Implemented inheritance to create a base class and derived classes with specific functionalities.

• Utilized polymorphism to allow objects of different classes to be treated as if they were of the same class.

• Implemented exception handling to handle errors and prevent program crashes.

• Used interfaces to define a set of methods that a ...read more
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Q5. Overloading vs overriding, practical uses
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Overloading is having multiple methods with the same name but different parameters. Overriding is having a method in a subclass with the same name and parameters as a method in the superclass.
• Overloading is used to provide different ways to call a method with different parameters

• Overriding is used to provide a specific implementation of a method in a subclass

• Overloading is resolved at compile-time while overriding is r...read more
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Q1. Clone a Todo Application UI using ReactJS, Sass
Ans. 
Clone a Todo Application UI using ReactJS, Sass
• Create a new ReactJS project using create-react-app

• Design the UI using Sass and implement it in ReactJS

• Use state and props to manage the todo list

• Add functionality to add, delete and mark tasks as complete

• Implement local storage to persist data

• Test the application thoroughly
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Q2. Explain the order of specifity in CSS classes, elements, ids, etc
Ans. 
Explanation of CSS specificity hierarchy
• Inline styles have the highest specificity

• IDs have higher specificity than classes and elements

• Multiple selectors with the same specificity are resolved by the order in which they appear in the stylesheet

• The universal selector (*) has the lowest specificity
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This round was more focused on the problem solving. 2 coding questions were asked. The round was for an hour

Q1. How does Server-Side Rendering work?
Ans. 
Server-Side Rendering (SSR) is the process of rendering web pages on the server and sending the HTML to the client.
• SSR improves website performance and SEO by reducing load times and providing search engines with fully rendered pages.

• React provides a library called ReactDOMServer that allows developers to render React components on the server.

• SSR requires a server-side framework or library, such as Next.js or Gatsby, t...read more
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It is easy to solve the Aptitude question and some identifying outputs of program.

Q1. What is class?and write a logic for object in a class.
Ans. 
A class is a blueprint for creating objects in object-oriented programming.
• A class defines the properties and behaviors of objects.

• An object is an instance of a class.

• Example: Class 'Car' can have properties like 'color' and 'model', and behaviors like 'drive' and 'stop'.
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Q2. 1.swap two numbers without using temp variable 2.Reverse the string.
Ans. 
Swap two numbers without using temp variable and reverse a string without using built-in functions.
• To swap two numbers without using temp variable, use bitwise XOR operation.

• To reverse a string without using built-in functions, use two pointers approach.

• Example for swapping numbers: a = a ^ b; b = a ^ b; a = a ^ b;

• Example for reversing a string: use two pointers to swap characters from start and end of the string.
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Now, I am preparing for the third round.
So, I don't know the Coding Question.

It was easy process and the questions is easy for freshers to clear the interview

Q1. Oops c# mvc asp.net web api asp.net core
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Q1. Tell me something about yourself
Ans. 
I am a passionate React Js developer with 5 years of experience in building user-friendly and responsive web applications.
• 5 years of experience in React Js development

• Skilled in building user-friendly and responsive web applications

• Passionate about frontend development
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Q2. Tell me about your work experience
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Q1. React application working
Ans. 
A React application is a web application built using the React JavaScript library for creating interactive user interfaces.
• React applications are built using components, which are reusable pieces of code that represent a part of the user interface.

• React uses a virtual DOM to efficiently update the actual DOM based on changes in the application state.

• React applications can be created using tools like Create React App or...read more
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Q2. Previous experience and projects
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Q1. Tell Me about yourself
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Q2. What is C# and coding.
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Q1. What is your CCTC?
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Q1. What is useState?
Ans. 
useState is a hook in React that allows functional components to have state.
• useState is a React hook used in functional components to manage state.

• It returns an array with the current state value and a function to update that value.

• Example: const [count, setCount] = useState(0);
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Q2. What's useEffect?
Ans. 
useEffect is a hook in React that allows performing side effects in function components.
• Used in React functional components to perform side effects

• Executes after render and after every update

• Can be used to fetch data, subscribe to events, update the DOM, etc.
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Q3. What is Redux and state management?
Ans. 
Redux is a predictable state container for JavaScript apps. It helps manage the state of an application in a centralized way.
• Redux is a state management library commonly used with React.

• It allows for a single source of truth for the state of an application.

• Actions are dispatched to update the state, and reducers specify how the state changes in response to actions.

• Redux DevTools can be used to track state changes and d...read more
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