How react js works under the hood

Under the hood, React.js leverages a virtual DOM (Document Object Model) and a diffing algorithm to efficiently update the user interface.

Here’s a high-level overview of how React.js works:

Component Structure:

React.js applications are built using reusable components. Each component represents a part of the user interface and can be composed of other components. Components can have properties (props) and maintain their own internal state.

Virtual DOM:

React.js introduces a virtual DOM, which is a lightweight representation of the actual DOM. The virtual DOM is a JavaScript object that mirrors the structure of the real DOM elements.

Rendering:

When a React component is rendered, it creates a virtual DOM representation of itself and its child components.

Reconciliation:

React employs a diffing algorithm to efficiently update the real DOM. When a component’s state or props change, React generates a new virtual DOM representation. It then compares the new virtual DOM with the previous one (diffing), identifying the minimal set of changes needed to update the real DOM.

Efficient Updates:

React optimizes the update process by minimizing DOM manipulations. Instead of updating the entire DOM tree, it selectively updates only the necessary parts. This approach improves performance by reducing the number of expensive operations required to update the UI.

Component Lifecycle Methods:

React provides lifecycle methods that allow developers to perform actions at specific points during a component’s lifecycle. These methods include componentDidMount, componentDidUpdate, and componentWillUnmount, among others, enabling developers to handle side effects, perform AJAX requests, or update the component state accordingly.

Event Handling:

React.js employs a synthetic event system to handle user interactions. It normalizes browser-specific events and provides a consistent API for handling events across different browsers.

Unidirectional Data Flow:

React follows a unidirectional data flow, also known as one-way binding. Data flows from parent components to child components via props. Child components can notify parent components of changes using callback functions passed as props.

By efficiently managing the virtual DOM and leveraging the diffing algorithm, React.js minimizes the direct manipulation of the real DOM, resulting in improved performance and a more responsive user interface.

Please note that this is a simplified explanation of how React.js works, and the framework’s internal implementation details may vary.