Q61. What is the purpose of `getDerivedStateFromProps()` lifecycle method?
The new static `getDerivedStateFromProps()` lifecycle method is invoked after a component is instantiated as well as before it is re-rendered. It can return an object to ...
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Q62. What is the purpose of `getSnapshotBeforeUpdate()` lifecycle method?
The new `getSnapshotBeforeUpdate()` lifecycle method is called right before DOM updates. The return value from this method will be passed as the third parameter to `compo...
Q63. What is the recommended ordering of methods in component class?
_Recommended_ ordering of methods from _mounting_ to _render stage_: 1. `static` methods 2. `constructor()` 3. `getChildContext()` 4. `componentWillMount()` 5. `component...
Q64. What is the difference between constructor and getInitialState?
You should initialize state in the constructor when using ES6 classes, and `getInitialState()` method when using `React.createClass()`. **Using ES6 classes:** ```javascri...
Q65. Can you force a component to re-render without calling setState?
By default, when your component's state or props change, your component will re-render. If your `render()` method depends on some other data, you can tell React that the ...
Q66. What is the difference between `super()` and `super(props)` in React using ES6 classes?
When you want to access `this.props` in `constructor()` then you should pass props to `super()` method. **Using `super(props)`:** ```javascript class MyComponent extends ...
Q67. How to listen to state changes?
The `componentDidUpdate` lifecycle method will be called when state changes. You can compare provided state and props values with current state and props to determine if ...
Q68. What are render props?
**Render Props** is a technique for sharing code/logic between components using a prop whose value is a function that returns a React element. Instead of duplicating stat...
Q69. How to dispatch an action on load?
You can dispatch an action in `componentDidMount()` method and in `render()` method you can verify the data. ```javascript class App extends Component { componentDidMount...
Q70. How to use `connect()` from React Redux?
You need to follow two steps to use your store in your container: 1. **Use `mapStateToProps()`:** It maps the state variables from your store to the props that you specif...