Walstar Technologies Reactjs Developer Interview Questions and Answers

Q1. Asked json web tokean authentication, authorisation. architecture of your project.
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Q2. Coding question- create crud app. Given array of objects. Render list in table. Do edit, delete, sort list on object property.
Ans. 
Create a CRUD app to render, edit, delete, and sort a list of objects in a table.
• Create a React component to render a table with data from the array of objects.

• Implement functions for editing and deleting objects from the list.

• Add functionality to sort the list based on object properties.

• Use state and props to manage data and re-render the table when changes occur.
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Q3. Difference bw rem, em, px. React hooks- useEffect, life cycle methods. use cases of hooks.
Ans. 
rem, em, px are units of measurement in CSS. useEffect is a React hook for side effects. Hooks are used for stateful logic in functional components.
• rem: relative to the font-size of the root element (html). Example: 1rem = 16px

• em: relative to the font-size of the element. Example: 2em = 32px if the font-size of the element is 16px

• px: fixed-size units. Example: font-size: 14px

• useEffect: React hook used for side effects ...read more
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1 hour online test ..

Q1. Programming related questions.
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Q1. DSA round (easy to medium)
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Q1. Technical+ hr round
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Q1. Technical questions.
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Q1. Life Cycle Methods off class components
Ans. 
Life cycle methods are special methods in class components that allow developers to run code at specific points in the component's life cycle.
• componentDidMount() is called after the component has been rendered to the DOM.

• componentDidUpdate() is called after the component's state or props have been updated.

• componentWillUnmount() is called before the component is removed from the DOM.
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Q2. Diffrence between FlatList and ScrollView
Ans. 
FlatList is optimized for rendering large lists efficiently by only rendering the items that are currently visible, while ScrollView renders all of its children at once.
• FlatList is more performant for long lists as it only renders the items that are currently visible on the screen.

• ScrollView renders all of its children at once, which can lead to performance issues with large datasets.

• FlatList supports key extraction fo...read more
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Q3. Real World Scenories Questions
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Q1. How make a queue using a stack
Ans. 
To implement a queue using a stack, use two stacks and simulate the queue operations.
• Use two stacks, one for enqueue operation and one for dequeue operation.

• For enqueue operation, simply push elements onto the stack used for enqueueing.

• For dequeue operation, if the dequeue stack is empty, pop all elements from enqueue stack and push onto dequeue stack.

• Then pop from the dequeue stack to simulate dequeue operation.
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Q2. Create a linked list
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A linked list is a data structure consisting of nodes where each node points to the next node in the sequence.
• Create a Node class with data and next pointer

• Initialize a head pointer to null

• Add nodes by updating next pointers

• Traverse the list by following next pointers
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It was ok. I was not able to solve all the questions.

Q1. Remove the last element from a linkedlist
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Q2. Some basic questions on oops dbms and os
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Mostly questions are start pattern related

Q1. Tell me 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

• Strong knowledge of HTML, CSS, and JavaScript

• Experience in building responsive web applications

• Passionate about creating user-friendly interfaces
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Q2. Why do you want to join this company?
Ans. 
I am impressed by the company's innovative projects and collaborative work culture.
• I admire the company's commitment to pushing boundaries in technology.

• I am excited about the opportunity to work with a talented team of developers.

• I believe my skills and experience align well with the company's goals and values.
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Normal apti questions test is easy

Opps,java basics, question on array and string as an array

Q1. Machine round collection framework pattern design array mid term SIngleton design pattern
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Q1. More dmbs and sql questions salary
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Simple question on maths

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 complex problems

• Key principles include encapsulation, inheritance, polymorphism, and abstraction

• Encapsulation ensures that the internal state of an object is hidden from the outside world

• Inheritance allows a class to inherit...read more
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Q2. Coding array questions
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