React virtual DOM

The React virtual DOM is a key concept in React that significantly enhances performance by minimizing direct manipulation of the real DOM. The real DOM is updated after comparing the virtual DOM with the current real DOM. To compare them, diffing algorithm is used. The comparison occurs in the memory. Here's a detailed look at the virtual DOM and how it works:

What is the Virtual DOM?

• The virtual DOM is a lightweight, in-memory representation of the real DOM.
• It is essentially a JavaScript object that React uses to model the UI.

How it Works:

• Initial Render: When a React component renders, React creates a virtual DOM tree that mimics the structure of the actual DOM.
• Updates: When the state or props of a component change, React creates a new virtual DOM tree. This new tree represents what the updated UI should look like.
• Diffing Algorithm: React compares the new virtual DOM tree with the previous one using a diffing algorithm. This process identifies what has changed.
• Reconciliation: Based on the diffing algorithm, React determines the most efficient way to update the real DOM. It then applies only the necessary changes to the real DOM.

Advantages:

• Performance: Direct manipulation of the real DOM is slow because it involves reflow and repaint operations, which are computationally expensive. The virtual DOM minimizes these operations by batching changes and applying them in an optimal way.
• Predictability: By abstracting the real DOM operations, the virtual DOM makes the UI updates predictable and easier to reason about.
• Efficiency: The virtual DOM reduces the number of direct manipulations to the real DOM, which enhances the overall performance and responsiveness of the application.

Workflow:

1. A component updates its state.
2. React creates a new virtual DOM tree.
3. The new virtual DOM tree is compared to the old one.
4. React identifies the differences (diffing).
5. React updates only the changed parts of the real DOM (reconciliation).

In summary, the virtual DOM is a powerful feature of React that optimizes the process of updating the user interface. By using a virtual representation of the DOM and applying changes in a calculated manner, React ensures efficient and smooth updates, improving the performance of web applications.