Amazon Development Centre India React Js Frontend Developer Interview Questions and Answers

Leetcode DSA problems

Goof amount of core js questions were asked

Q1. Started with simple questions like hoisting and virtual DOM, then progressed to event loop microtask queue and other concepts.
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Q2. Asked about debouncing and throttle (I mentioned them in projects). Then told me to write polyfill for those. What is reconciliation in React and how is it working after React 16 and how was it working ear...read more
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Q3. Couple of output questions based on closure.
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Q1. Coding questions on React + JS
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Q1. What is Debouncing in JavaScript?
Ans. 
Debouncing in JavaScript is a technique used to limit the number of times a function is called in a short period of time.
• Debouncing is used to improve performance and prevent unnecessary function calls.

• It delays the execution of a function until after a certain amount of time has passed since the last invocation.

• It is commonly used in scenarios like search bars, scroll events, and input validation.

• Debouncing can be imp...read more
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Q2. What is an Arrow Function?
Ans. 
Arrow functions are a concise way to write functions in JavaScript.
• Arrow functions have a shorter syntax compared to regular functions.

• They do not have their own 'this' value.

• Arrow functions are always anonymous.

• They are commonly used in React components for event handlers and callbacks.
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The first round consisted of a coding exercise along with fundamental questions related to React Native, JavaScript, and inquiries about objects and arrays.

Q1. Native modules, useRef, Flatlist
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Q1. Javascript basics
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Q1. React native basics
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Q2. Scroll vs flatlist
Ans. 
FlatList is more efficient for rendering large lists with better performance compared to ScrollView.
• FlatList is optimized for rendering long lists by only rendering 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 lists.

• FlatList also provides built-in support for pull-to-refresh, infinite scrolling, and item separators.

• Scr...read more
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Q3. Design carousel in react native
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Designing a carousel in React Native involves creating a horizontal scroll view with swipe functionality.
• Use ScrollView component with horizontal prop to create the carousel layout.

• Render multiple items inside the ScrollView to display carousel content.

• Implement swipe gestures to navigate between carousel items.

• Consider using libraries like 'react-native-snap-carousel' for additional features and customization.
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It was based on Javascript. Some web basics like CORS , react rendering patterns. Then JS based output questions. Some were based on JS promise. Function currying.