Infosys Reactjs Developer Interview Questions, Process, and Tips for Experienced

Q1. What are the benefits of React?
Ans. 
React offers a component-based architecture, virtual DOM for performance optimization, and a strong community support.
• Component-based architecture allows for reusability and easier maintenance of code.

• Virtual DOM helps in improving performance by only updating the necessary parts of the actual DOM.

• React has a strong community support with a vast ecosystem of libraries and tools available.

• React allows for server-side re...read more
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Q2. Difference between state and props?
Ans. 
State is mutable and managed within the component, while props are immutable and passed from parent component.
• State is managed within the component and can be changed using setState() method

• Props are passed from parent component to child component and cannot be changed by the child component

• State is used for internal component data management, while props are used for passing data from parent to child components
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Q3. What is useReducer and UseContext api?
Ans. 
useReducer is a React hook that manages state changes through a specified reducer function. useContext is a hook that allows access to a context object.
• useReducer is used for managing complex state logic in React applications.

• It takes in a reducer function and an initial state, and returns the current state and a dispatch function.

• Example: const [state, dispatch] = useReducer(reducer, initialState);

• useContext is used f...read more
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Q4. What is one way data binding?
Ans. 
One way data binding is a unidirectional flow of data from the model to the view in React applications.
• Data flows from the model (or source of truth) to the view, but not vice versa.

• Changes in the model automatically update the view, but changes in the view do not affect the model.

• Helps in maintaining a clear and predictable data flow in React components.
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Q5. Tell me hooks you have used?
Ans. 
I have used useState, useEffect, useContext, useReducer, and useRef hooks in my projects.
• useState - for managing state in functional components

• useEffect - for handling side effects in functional components

• useContext - for accessing context in functional components

• useReducer - for managing complex state logic in functional components

• useRef - for accessing DOM elements or storing mutable values
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Q6. What is redux middleware
Ans. 
Redux middleware is a function that intercepts actions before they reach the reducer.
• Middleware can be used for logging, crash reporting, asynchronous API calls, etc.

• It sits between the action dispatch and the reducer.

• Examples of popular middleware include redux-thunk and redux-saga.
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Q1. Questions related to Projects
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Q2. Git commands: How to commit ,merge code, how to resolve merge conflicts
Ans. 
Git commands for committing, merging code, and resolving merge conflicts
• To commit code: git commit -m 'Commit message'

• To merge code from a branch: git merge branch_name

• To resolve merge conflicts: manually edit the conflicting files, add changes, and then commit the merge
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It's 10 multiple-choice question with low,medium, and difficult range levels.

Q1. What is conditional rendering in React? What are closures? OOPS concept in JavaScript. What is ACID in database? Stack vs Heap
Ans. 
Conditional rendering in React allows components to render different elements or components based on certain conditions.
• Conditional rendering is achieved using JavaScript expressions inside JSX.

• Common conditional rendering techniques include using if statements, ternary operators, and logical && operator.

• Example: rendering a component only if a certain condition is met - {condition ? : null}
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Q2. In react you can conditionally render component like when and which component to render by using if condition and other.
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Q1. Difference between var and let, difference between redux and flux
Ans. 
Var is function scoped, let is block scoped. Redux is a predictable state container, Flux is an architecture pattern.
• Var can be redeclared and updated within its scope, let cannot be redeclared but can be updated within its scope

• Redux has a single store for the entire application, while Flux has multiple stores

• Redux uses a unidirectional data flow, while Flux uses a bidirectional data flow

• Redux has middleware for handl...read more
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Q2. Output based questions on var and let.
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