Q41. How does React batch multiple state updates?
React prevents component from re-rendering for each and every state update by grouping multiple state updates within an event handler. This strategy improves the applicat...
Technical Question Bank · Peer-Reviewed
Job Interview Questions and Answers Directory
Search and filter frequently asked interview questions across technical, programming, and behavioral domains. Tailor your interview preparation by difficulty for freshers or experienced developers (59 available).
Active:
Tag: performance ×
Q42. What will happen by defining nested function components?
Technically it is possible to write nested function components but it is not suggested to write nested function definitions. Because it leads to unexpected bugs and perfo...
Q43. Can you describe the useMemo() Hook?
The `useMemo()` Hook in React is used to **optimize performance** by **memoizing the result of expensive calculations**. It ensures that a function is **only re-executed ...
Q44. What happens if you use useLayoutEffect for non-layout logic?
Using `useLayoutEffect` for logic **unrelated to layout or visual DOM changes** (such as logging, data fetching, or analytics) is **not recommended**. It can lead to **pe...
Q45. What is V8 JavaScript engine?
V8 is an open source high-performance JavaScript engine used by the Google Chrome browser, written in C++. It is also being used in the node.js project. It implements ECM...
Q46. Does useMemo prevent re-rendering of child components?
The `useMemo` hook **does not directly prevent re-rendering of child components**. Its main purpose is to memoize the result of an expensive computation so that it doesn’...
Q47. Why do you need to avoid with statement?
JavaScript's with statement was intended to provide a shorthand for writing recurring accesses to objects. So it can help reduce file size by reducing the need to repeat ...
Q48. What is the useDeferredValue hook?
The `useDeferredValue` hook is used to **defer updating a part of the UI** to keep other parts responsive. It accepts a value and returns a "deferred" version of that val...
Q49. What are the key features introduced in React 18?
React 18, released in March 2022, introduced several groundbreaking features focused on performance and user experience: #### 1. **Automatic Batching** Batch multiple sta...
Q50. Why is normalized state important for performance?
1. **O(1) lookups by ID** instead of scanning/`find()`-ing through an array every time a component needs one item. 2. **Updates are localized**: changing one entity only ...