Fisdom React Js Frontend Developer Interview Questions and Answers

Q1. Create Observer class
Ans. 
Create an Observer class
• Observer class is used to notify changes to multiple objects

• It maintains a list of objects that need to be notified

• It has methods to add, remove and notify observers

• Example: Weather station notifying multiple displays
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Q2. Create Pagination component similar to mui component
Ans. 
Create a pagination component similar to mui component.
• Use React to create a reusable pagination component

• Include props for total number of pages, current page, and page size

• Use Material UI styles for consistent look and feel

• Add event handlers for page changes

• Test component thoroughly
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Implement some LLD and use clean code formulas

Better be prepared for all deep dive questions about tech and project you worked

Round duration - 30 minutes
Round difficulty - Easy

Basic questioning about my work experiences, things I have developed and created, my work experience(internships). The challenges which I have faced and how I overcame them. Basic questions about some android concepts

Q1. What puzzles were asked during the interview, and can you describe the projects you discussed?
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Round duration - 45 minutes
Round difficulty - Medium

The interviewer was very friendly and asked about various things and tried to judge my understanding of the projects and how deep I know about the concepts I have implemented in my projects

Q1. RxJava
RxJava
Ans. 
RxJava is a popular library for composing asynchronous and event-based programs using observable sequences.
• RxJava provides a functional API for working with asynchronous data streams.

• It uses Observables to emit items and notify subscribers.

• Operators can be used to transform, filter, and combine these streams of data.

• Schedulers are used to control the threading behavior of these operations.

• Example: Creating an Observabl...read more
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Round duration - 40 minutes
Round difficulty - Medium

This was a system design round

Q1. Can you explain the fragment lifecycle in Android system design?
Ans. 
Fragment lifecycle in Android involves various states and methods for managing UI components.
• Fragments have several lifecycle states such as created, started, resumed, paused, stopped, and destroyed.

• Methods like onCreate(), onCreateView(), onResume(), onPause(), onStop(), onDestroy() are used to manage fragment lifecycle.

• Fragment lifecycle is closely tied to the hosting Activity's lifecycle.

• Example: When a fragment is ...read more
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There was aptitude test out of which 12 candidate selected

Q1. Asked me about my project in details
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Q2. What does group by do in SQL.
Ans. 
GROUP BY in SQL is used to group rows that have the same values into summary rows.
• GROUP BY is used with aggregate functions like COUNT, SUM, AVG, etc.

• It is used to summarize data by grouping rows based on specified columns.

• GROUP BY is often used in conjunction with the SELECT statement.
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Q3. Then asked about spring boot
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Q1. Explain OOPS Concept ?
Ans. 
OOPS (Object-Oriented Programming) is a programming paradigm based on the concept of objects, which can contain data and code.
• OOPS focuses on creating objects that interact with each other to solve problems.

• It involves concepts like classes, objects, inheritance, polymorphism, and encapsulation.

• For example, a class 'Car' can have objects like 'Toyota', 'Honda', etc., each with their own properties and methods.

• Inheritan...read more
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Q1. General questions about past experiences, the skills i gathered and salary negotiation part ( Virtual interview )
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Q1. Interview with VP sales ( Virtual Interview)
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Q1. Interview with Senior VP about general understanding of finances
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Hacker rank test, with a medium level Data Structure problem

Q1. This round was specific to Javascript.
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Q2. Asked, Function currying, closure, hoisting, promise
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Q1. Designing round, where I was asked to built a feature with React. Also asked Javascript problems
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Q1. Web performance mechanism and how can I optimise the performance, these questions were asked
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Q2. Build a websocket, and questions about React JS
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Q1. What is dependency injection
Ans. 
Dependency injection is a design pattern in which components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by providing mock dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.
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Q2. What is state in react
Ans. 
State in React is a JavaScript object that stores data and determines how a component renders and behaves.
• State is mutable and can be updated using the setState() method

• State should be used for data that will change over time and affect the component's rendering

• State should not be modified directly, use setState() instead
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