React utilizes the virtual DOM to enhance performance by minimizing direct manipulations of the actual browser DOM. Here's how this process unfolds:
Understanding the Virtual DOM
The virtual DOM is essentially a lightweight copy of the actual DOM, represented as a JavaScript object. Changes in the React application don't directly impact the browser's DOM. Instead, React makes adjustments to this virtual representation first.
The Reconciliation Process
State and Prop Changes
Whenever the state or props of a React component change, React initiates a process of updating the user interface. This process involves the following steps:
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Virtual DOM Update: According to the reference, "Whenever the state or props change, before making updates to the real DOM, React first updates the Virtual DOM." React doesn’t directly manipulate the browser’s DOM, instead, it creates a fresh copy of the virtual DOM, incorporating these changes.
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Diffing: React then performs a "diffing" process. During diffing, React calculates the differences between the previous virtual DOM and the newly updated one. This comparison highlights what has changed rather than re-rendering the whole DOM. The goal is to find the most efficient way to update the user interface.
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Patching: After identifying the specific changes, React applies these changes to the real browser DOM. This targeted update process is known as "patching." This approach avoids unnecessary updates and re-renders, leading to better performance.
- Example: Instead of completely rebuilding a list, if an item is added or removed, React will only alter the list nodes that have changed.
Benefits of the Virtual DOM
Using a virtual DOM leads to significant improvements in performance:
- Reduced DOM Manipulation: Direct manipulations of the browser DOM are expensive. React minimizes these expensive operations by performing calculations on the virtual DOM and then updating the real DOM in the most optimized way.
- Faster Rendering: The diffing and patching algorithm allows React to update the actual DOM more rapidly.
- Increased Performance: This efficient updating process results in better performance of React applications.
Summary
In summary, React employs the virtual DOM as an intermediary step to identify and apply only the necessary changes to the real DOM, optimizing rendering performance, avoiding unnecessary changes, and making the application perform more efficiently.
