Sigma Solve React Developer Interview Questions and Answers

Q1. What is enums in typescript, difference between shallow and deep copy, what is virtual dom, what are closures, some psuedo codes, react machine coding. and other basic javascript questions.
Ans. 
Enums in TypeScript are a way to define a set of named constants. Shallow copy only copies the reference, while deep copy creates a new object. Virtual DOM is a lightweight copy of the actual DOM. Closures are functions that have access to their own scope and the scope of their containing function.
• Enums in TypeScript are used to define a set of named constants. For example, enum Color { Red, Green, Blue }

• Shallow copy c...read more
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Q1. Testing related questions, and other javascript and react 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. What is observable and promises
Ans. 
Observables and promises are both used for handling asynchronous operations in JavaScript.
• Observables are used for handling multiple values over time, while promises are used for handling a single value at a time.

• Observables can be cancelled, while promises cannot be cancelled.

• Promises have a built-in mechanism for error handling using the catch method, while observables use the error callback function.

• Observables are ...read more
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