How Virtual DOM Works in React

Virtual DOM in React

The Virtual DOM is a key concept in React that enhances performance by minimizing unnecessary browser DOM updates. Here's a breakdown of how it works.

  1. Initial Rendering

    • React creates a lightweight representation of the actual DOM called the Virtual DOM.
    • When you write JSX and render components, React constructs a Virtual DOM tree that mirrors the real DOM.
  2. Updating the Virtual DOM

    • When a component's state or props change, React doesn't immediately update the real DOM. Instead, it re-renders the component and generates a new Virtual DOM representation of the entire UI.
  3. Diffing Algorithm

    • React performs a "diffing" process by comparing the updated Virtual DOM with a snapshot of the previous Virtual DOM.
    • It identifies the differences (or "diffs") between the new and previous Virtual DOM trees efficiently.
  4. Minimizing DOM Manipulation

    • Once React identifies the differences, it calculates the most efficient way to update the real DOM to match the new Virtual DOM.
    • React creates a batch of updates and applies them to the actual DOM in a single pass, reducing the number of DOM manipulations needed.
  5. Updating the Real DOM

    • Finally, React updates only the parts of the real DOM that have changed, resulting in optimized and minimal updates to the browser's DOM.
  6. Performance Benefits

    • The Virtual DOM minimizes direct interaction with the browser's expensive DOM operations, making updates faster.
    • It also helps in optimizing performance by bundling multiple updates together and applying them in batches.

This process of reconciling the Virtual DOM with the real DOM efficiently handles updates, ensuring a smoother user experience while abstracting away many of the complexities involved in directly manipulating the DOM.

The key takeaway is that React's Virtual DOM acts as an intermediary between the application and the actual browser DOM, optimizing the process of updating the UI by minimizing unnecessary DOM manipulations.


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