Q11. How does useContext works? Explain with an example
The `useContext` hook can be used for authentication state management across multiple components and pages in a React application. Let's build a simple authentication flo...
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Q12. Can You Use Multiple Contexts in One Component?
Yes, it is possible. You can use multiple contexts inside the same component by calling useContext multiple times, once for each context. It can be achieved with below st...
Q13. What's a common pitfall when using useContext with objects?
A **common pitfall** when using `useContext` with objects is **triggering unnecessary re-renders** across all consuming components — even when only part of the context va...
Q14. What would the context value be for no matching provider?
When a component calls `useContext(SomeContext)` but **no matching** `` **is present higher up in the component tree**, the **default value** passed to `React.createConte...
Q15. What is the use() hook in React 19?
The `use()` hook allows you to read the value of a resource (Promise or Context) during render, with Suspense integration. #### Reading Promises ```jsx import { use, Susp...
Q16. Does `React.memo` prevent Context consumers from re-rendering?
**No.** `React.memo` only performs a shallow comparison of a component's **props** — it has no visibility into context. If a component reads a value via `useContext`/`Con...
Q17. How would you create a reusable Context?
A **reusable Context** bundles the `createContext` call, its `Provider` (with local state/logic), and a custom hook to consume it into a single module. This hides the raw...
Q18. What is context?
_Context_ provides a way to pass data through the component tree without having to pass props down manually at every level. For example, authenticated users, locale prefe...
Q19. How are error boundaries handled in React v15?
**⚠️ LEGACY:** This question is only relevant for historical context. React v15 is extremely outdated (released in 2016). React v15 provided very basic support for _error...
Q20. Is it good to use `setState()` in `componentWillMount()` method?
**⚠️ DEPRECATED:** `componentWillMount()` has been removed in React 17+. This question is only relevant for legacy React applications. **Historical Context:** While it wa...