upGrad Front end Developer Interview Questions and Answers

Q1. What is memoization in react
Ans. 
Memoization is a technique used to optimize performance by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
• Memoization helps to avoid redundant calculations by storing the results of function calls.

• It can be implemented using libraries like 'memo' in React or manually by storing results in a cache.

• Memoization is commonly used in React to optimize renderin...read more
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Q2. Promise vs promise all
Ans. 
Promise is used for asynchronous operations with a single result, while Promise.all is used for handling multiple promises simultaneously.
• Promise is used for handling asynchronous operations with a single result

• Promise.all is used for handling multiple promises simultaneously

• Promise.all waits for all promises to resolve or any one to reject
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Q3. Minimum sum path
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Q4. React Vs Angular
Ans. 
React is a lightweight library for building user interfaces, while Angular is a full-fledged framework with more features and conventions.
• React is more flexible and allows for more control over the code structure.

• Angular provides more out-of-the-box features like routing, forms, and HTTP client.

• React is easier to learn for beginners due to its simplicity.

• Angular has a steeper learning curve but offers more built-in too...read more
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Q5. In what cases will you use Promise.all
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Promise.all is used to handle multiple promises concurrently and wait for all of them to resolve.
• Use Promise.all when you need to make multiple asynchronous calls and wait for all of them to complete before proceeding.

• It is useful for scenarios like fetching data from multiple APIs and processing them together.

• Example: Promise.all([fetch('url1'), fetch('url2')]).then(responses => { // handle responses })
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Q1. Situational questions
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Q2. Questions related to day to day work
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DSA, React, JavaScript, Rest API, Redux, VUE js,

Q1. What is virtual DOM?
Ans. 
Virtual DOM is a lightweight copy of the actual DOM used for efficient updates.
• Virtual DOM is a concept used in React to improve performance.

• It is a lightweight copy of the actual DOM.

• It is used to minimize the number of updates needed to be made to the actual DOM.

• When a change is made to the virtual DOM, React compares it with the previous version and only updates the necessary changes to the actual DOM.

• This results i...read more
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Q2. What is Redux?How to implement Redux?
Ans. 
Redux is a predictable state container for JavaScript apps.
• Redux is a state management library for JavaScript applications.

• It helps in managing the state of an application in a predictable way.

• Redux follows a unidirectional data flow pattern.

• To implement Redux, we need to define actions, reducers, and a store.

• Actions are plain JavaScript objects that describe what happened.

• Reducers specify how the application's state c...read more
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Q1. Asked about lazy loading ?
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Q2. What do you mean by denouncing?
Ans. 
Denouncing refers to publicly declaring something as wrong or evil.
• Denouncing is the act of condemning or criticizing something publicly.

• It is often done to express disapproval or to call attention to a wrongdoing.

• Examples include denouncing acts of violence, discrimination, or corruption.

• Denouncing can also be used in political contexts to criticize policies or actions of a government.
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Q3. How redux state are cleaned ?
Ans. 
Redux state can be cleaned by dispatching an action to reset the state to its initial values.
• Dispatching an action with type 'RESET_STATE'

• Updating the reducer to return the initial state when 'RESET_STATE' action is dispatched
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Q4. Sorting the array
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Q5. Make pagination and sorting coding questions.
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Q1. How Netflix video loading works it was of system design
Ans. 
Netflix uses a content delivery network (CDN) to efficiently load videos based on user location and network conditions.
• Netflix uses a distributed network of servers to store and deliver video content closer to users for faster loading times.

• Content is cached on servers located in various regions to reduce latency and improve streaming quality.

• Netflix employs adaptive bitrate streaming to adjust video quality based on a...read more
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Q2. How can we download csv file of more then 1000mb and show the data that is downloaded while downloading?
Ans. 
To download a large CSV file (>1000mb) and show the data while downloading, use streaming and pagination techniques.
• Implement streaming to download the file in chunks instead of all at once.

• Use pagination to display the downloaded data in parts as it is being downloaded.

• Consider using libraries like PapaParse for parsing CSV data efficiently.

• Show a progress bar or indicator to inform the user about the download status.
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Q3. Pattern question
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Q4. React assingment
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Api Call with pagination support, Card with button.

Same , Just changed the difficulties

React js Assessments