Intro to Virtual DOM for React Devs

Do you know JSX is converted before showing up in web page?

In React, the Virtual DOM (Document Object Model) is a lightweight JavaScript representation of the actual DOM. It is an abstraction that allows React to efficiently update and render components by comparing changes between the current Virtual DOM and a new one.

Learn more about DOM :

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When to use?

• Best Fit: Applications with dynamic, frequently changing UIs, such as dashboards, social media feeds, or SPAs.

• Overkill: Static websites or applications with minimal interactivity.

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How to use?

• React creates a copy of the real DOM (Virtual DOM).

• When the state or props of a component change, React updates the Virtual DOM first.

• React then performs a "diffing" algorithm to calculate the minimal set of changes (differences) between the old Virtual DOM and the new one.

• Finally, React applies only those specific changes to the actual DOM.

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Where to use?

The Virtual DOM in React is used to enhance performance and optimize updates to the user interface (UI). React automatically uses the Virtual DOM internally, so as a developer, you don't need to manage it directly. Instead, you leverage it by writing efficient React components. Here's where and how the Virtual DOM proves beneficial:

• Dynamic UI Updates

• Efficient DOM Manipulation

• Single Page Applications

• Component Re-rendering

• Complex Applications

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Pros

1. Performance Optimisation

   • React updates only the changed parts of the real DOM by comparing differences between the Virtual DOM and the previous version. This makes updates faster and reduces unnecessary re-renders.

2. Improved Developer Productivity

   • Abstracts the complexity of direct DOM manipulation. Developers write declarative UI code, and React efficiently handles updates.

3. Cross-Browser Compatibility

   • The Virtual DOM smoothens out browser inconsistencies by providing a unified way to interact with the DOM.

4. Efficient UI Updates

   • Allows for smoother and more responsive UIs, especially in applications with dynamic data and frequent updates.

5. Predictable State Management

   • React’s reconciliation process ensures consistent updates, avoiding issues like unexpected behaviours in complex DOM updates.

6. Simplified Debugging

   • The abstraction provided by the Virtual DOM simplifies understanding and debugging UI changes compared to directly dealing with the real DOM.

Cons

1. Initial Performance Overhead

   • Generating the Virtual DOM and performing the diffing algorithm adds overhead, which can be noticeable for very simple or static applications.

2. Learning Curve

   • Developers new to React need to understand concepts like the Virtual DOM, reconciliation, and component lifecycle.

3. Abstraction Limitations

   • Being an abstraction, the Virtual DOM is less flexible than manually controlling the real DOM in highly customized scenarios.

4. Memory Usage

   • Maintaining a Virtual DOM copy increases memory consumption, especially in large-scale applications with complex components.

5. Not Always Necessary

   • For small applications or static content, the benefits of the Virtual DOM may not outweigh the extra computational overhead.

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Browser support

React and its Virtual DOM work on the following browsers:

1. Modern Browsers:

   • Google Chrome (latest versions)

   • Mozilla Firefox (latest versions)

   • Microsoft Edge (latest versions)

   • Safari (latest versions)

   • Opera (latest versions)

2. Mobile Browsers:

   • iOS Safari (latest versions)

   • Android Browser (latest versions)

   • Chrome for Android

   • Firefox for Android

3. Legacy Browsers:

   • React supports Internet Explorer 9+ (but IE 11+ is recommended for better performance and compatibility).

   • we can also use a Polyfill to support it :

     https://github.com/facebook/create-react-app/blob/main/packages/react-app-polyfill/README.md

Next : Blog on Diffing Algorithm for React Devs , stay tuned!