React.js Questions

React is a JavaScript library for building component-based user interfaces. It helps create fast, reusable UI for web apps.

JSX is JavaScript XML-like syntax used to write UI inside JavaScript. Babel converts JSX into React.createElement calls.

Components are reusable UI blocks. They can be functional or class-based, but modern React mainly uses functional components.

Props are read-only values passed from a parent component to a child component. They help make components reusable.

State is internal data managed by a component. When state changes, React re-renders the component.

Props come from the parent and are read-only. State belongs to the component and can change using setters like setState or useState.