Q121. Would you put all API data into Redux?
**No** — not by default. Server data (see [client state vs server state](#what-is-the-difference-between-client-state-and-server-state)) has different needs than plain cl...
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Q122. Why should we not update the state directly?
If you try to update the state directly then it won't re-render the component. ```javascript //Wrong this.state.message = "Hello world"; ``` Instead use `setState()` meth...
Q123. What is the purpose of callback function as an argument of `setState()`?
The callback function provided as the second argument to `setState` is executed after the state has been updated and the component has re-rendered. Because `setState()` i...
Q124. What are the different phases of component lifecycle?
The component lifecycle has three distinct lifecycle phases: 1. **Mounting:** The component is ready to mount in the browser DOM. This phase covers initialization from `c...
Q125. What are the lifecycle methods of React?
Before React 16.3 - **componentWillMount:** Executed before rendering and is used for App level configuration in your root component. - **componentDidMount:** Executed af...
Q126. How to set state with a dynamic key name?
If you are using ES6 or the Babel transpiler to transform your JSX code then you can accomplish this with _computed property names_. ```javascript handleInputChange(event...
Q127. What will happen if you use `setState()` in constructor?
When you use `setState()`, then apart from assigning to the object state React also re-renders the component and all its children. You would get error like this: _Can onl...
Q128. 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...
Q129. What will happen if you use props in initial state?
If the props on the component are changed without the component being refreshed, the new prop value will never be displayed because the constructor function will never up...
Q130. What is the lifecycle methods order in mounting?
The lifecycle methods are called in the following order when an instance of a component is being created and inserted into the DOM. 1. `constructor()` 2. `static getDeriv...