Virtual DOM in React

The virtual DOM (Virtual Document Object Model) is a JavaScript representation of the Document Object Model (DOM) that helps improve the performance of web frameworks. It is particularly in frameworks like React. It refers to a lightweight, in-memory representation of the actual DOM.

Concepts Related to Virtual DOM

1. Efficient Updates:
   • The virtual DOM helps optimize performance by minimizing the number of direct updates to the real DOM. Instead of re-rendering the entire UI, React updates only the parts that need changing.
2. Reconciliation Algorithm:
   • React uses a heuristic algorithm to efficiently compare trees and find differences. It assumes that changes are likely to be localized, allowing it to avoid deep comparisons and focus only on relevant parts of the tree.
3. Component-Based Architecture:
   • React is component-based architecture fits well with the virtual DOM approach. Each component can maintain its own state and be re-rendered independently, allowing React to efficiently manage updates and maintain a smooth user experience.
4. Declarative UI:
   • React promotes a declarative approach to building UIs, where you describe what the UI should look like based on the current state. The virtual DOM handles the intricacies of updating the real DOM to match this description.

How Virtual DOM Works

1. Virtual DOM Creation: When you create or update a component in React, it first renders the component to a virtual DOM instead of directly manipulating the real DOM. This virtual DOM is a JavaScript object that mimics the structure of the actual DOM.
2. Diffing Algorithm: React then compares the virtual DOM with the previous version using a process called “diffing.” It determines what has changed by comparing the new virtual DOM tree with the previous one.
3. Update Real DOM: After identifying the differences, React updates only those parts of the real DOM that have changed. This process is much more efficient than updating the entire real DOM.

Differences between Virtual DOM and Real DOM

Real DOM: Directly represents the structure of the UI and requires updates to the actual DOM elements. This can be slow and inefficient, especially with frequent updates.

Virtual DOM: Acts as an intermediary that efficiently calculates and applies only the necessary changes to the real DOM, improving performance and maintainability.

Virtual DOM	Real DOM
It is a lightweight copy of the original DOM	It is a tree representation of HTML elements
It is maintained by JavaScript libraries	It is maintained by the browser after parsing HTML elements
After manipulation it only re-renders changed elements	After manipulation, it re-render the entire DOM
Updates are lightweight	Updates are heavyweight
Commonly used in JavaScript libraries/frameworks like React	Used in the core functionality of web browsers
Highly efficient as it performs batch updates	Less efficient due to re-rendering of DOM after each update

Benefits of Virtual DOM in Practice

• Improved Performance: Reduces the overhead of frequent and costly DOM updates, leading to faster rendering times and a more responsive application.
• Predictable Updates: Makes it easier to manage and predict UI changes, as the virtual DOM abstracts away the complexities of direct DOM manipulation.
• Enhanced Development Experience: Simplifies the development process by allowing developers to focus on the desired state of the UI without worrying about manual DOM updates.