Virtual DOM

The Virtual DOM is a lightweight JavaScript representation of the real DOM in React.js. It is one of the key concepts that makes React efficient for building user interfaces.

How the Virtual DOM Works:

1. Virtual Representation:
   • When a component’s state or props change, React creates a virtual representation of the updated UI, which is a tree-like structure in memory.
   • This virtual DOM is not rendered to the screen but exists only in memory.
2. Diffing Algorithm:
   • React uses a reconciliation process to compare the new virtual DOM with the previous version.
   • This comparison is efficient due to React’s diffing algorithm, which identifies the changes (minimal differences) between the two versions of the virtual DOM.
3. Batch Updates:
   • After identifying the changes, React batches these updates to optimize performance.
4. Updating the Real DOM:
   • React updates only the parts of the real DOM that have changed, minimizing costly operations like re-rendering the entire UI.
   • This is achieved by mapping the changes in the virtual DOM to the real DOM using a library like ReactDOM.

Benefits of the Virtual DOM:

• Improved Performance: Only updates necessary parts of the real DOM.
• Declarative UI: Developers describe what the UI should look like, and React handles the updates efficiently.
• Cross-Browser Compatibility: Abstracts away differences in browser DOM implementations.

In summary, the Virtual DOM is a core feature of React that enables it to efficiently manage UI updates by reducing direct manipulation of the real DOM.