React Questions

Events are not handled in functional components, only in class components

By creating separate event listener functions outside the component

Using inline event handlers directly in JSX

By defining methods inside the component class

An error will be thrown, and the application will crash.

Nothing will happen; the state will remain unchanged.

The component will re-render, and the state change will be reflected correctly.

The component will re-render, but the state change won't be reflected.

By using browser alerts to notify the user of invalid input.

By logging errors to the console for debugging purposes.

By conditionally rendering error messages based on validation results.

By relying solely on HTML5's built-in validation error messages.

React components don't handle events directly; you must use a library.

Defining separate event handler methods within the component

Using the addEventListener method like in vanilla JavaScript

Using inline event handlers like onClick={handleClick}

Direct DOM manipulation can lead to inconsistencies between the actual DOM and React's virtual DOM

React's event system automatically prevents DOM manipulation

DOM manipulation is slow and inefficient in modern browsers

React doesn't have access to the DOM, so manipulation is impossible

By defining methods on the class that act as event handlers

Class components cannot handle events; only functional components can

Using inline arrow functions directly in the JSX

By relying on external state management libraries for event handling

Using this.state = { new state } directly

Using the useState hook

By calling this.setState({ new state })

By modifying this.props object

To enable asynchronous event handling in React components

To directly manipulate the DOM without using React's virtual DOM

To prevent default browser actions for all events

To provide a cross-browser consistent interface for handling DOM events

export default function MyComponent(props = { name: 'John' }) { }

function MyComponent(props) { props.defaultProps = { name: 'John' }; }

defaultProps = { name: 'John' }(MyComponent);

MyComponent.defaultProps = { name: 'John' };

To style form elements based on user input.

To automatically submit the form when all fields are filled.

To ensure data integrity and prevent invalid submissions.

To send data to the server for validation.