What is Virtual DOM in ReactJS

What is a Document Object Model (DOM)

Document Object Model, or DOM, refers to a computer interface based on a document model of structures as a tree of objects. This enables the running programs to update content structure and view the web pages as desired. It depicts the document’s structure, providing for its components, attributes, and the text as objects of the tree. Each node can be accessed and manipulated with JavaScript; as a result, it is possible to update a web page without the need to load a new page.

The DOM is critical in web development because it is the intermediate process between mere HTML and interactive online applications. Due to the DOM, developers can manipulate the site’s construction, modify elements that have been created or delete contents, respond to activities made by users, and make pages dynamic.

How Does Re-rendering in DOM Impact Performance

Re-rendering in the DOM significantly impacts performance, especially in complex online apps. Whenever the DOM is dirty, the browser requires that it crash course for styles, rearrange the page, and repaint the page’s elements. The two processes that potentially give performance issues due to the resources required are Reflow and Repaint, mainly when many changes are made, or undesirable parts of a website encompass a large area.

Re-rendering should only occur occasionally to avoid the website becoming slow and consuming too much memory. Improvements to DOM updates, less frequent layouts, and possible solutions such as batch updates or virtualization can help ease these performance problems. Otherwise, re-rendering can become problematic as it is the primary consideration for getting web applications to work and respond correctly.

Disadvantages of Real DOM

The Real DOM, or Document Object Model, has various drawbacks that might influence performance and efficiency in web development.

Performance Overhead

When the DOM adjustments, the browser must replace the entire document. This includes recalculating styles, rearranging items, and repainting the display. These revisions may be time-consuming and cause full-size delays for huge or complicated papers.

Inefficient Re-rendering

When several adjustments co-arise, the real DOM re-renders the whole web page, even supposing only a tiny element has been altered. This inefficiency increases computational and rendering fees, affecting overall performance.

Layout Thrashing

Frequent DOM updates can create layout thrashing, which occurs when the browser must constantly recalculate layouts and styles due to fast, sequential changes. This can provide twitchy or stuttering user interfaces.

Memory Usage

Frequent DOM operations boom reminiscence use. As the DOM increases, extra memory is required to address the nodes and their connections, affecting the browser’s ordinary performance.

Complexity in Optimisation

Optimizing the velocity of DOM in React necessitates careful control of updates and re-renders, which may be complex and blunders-prone. Developers often need to appoint various solutions to mitigate the effects of those performance difficulties.

Lack of Predictability

The Real DOM provides a challenging approach for batch updating or optimizing how adjustments are implemented. This volatility may make it hard to assure steady performance throughout several devices and browsers.

Limited Interaction

In excessive interplay or frequent updates, the Real DOM’s inefficiency might bring sluggish or unresponsive interfaces, reducing overall consumer enjoyment.

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What is the Virtual DOM

The Virtual DOM (VDOM) is an abstraction of the Real DOM utilized in net applications to enhance update and rendering performance. Instead of immediately modifying the Real DOM, which may be high-priced and wasteful, the Virtual DOM generates a lightweight, in-reminiscence version of the person interface. When changes arise, they will be carried out to the Virtual DOM. This revised representation is then compared to a prior version via a procedure called “diffing.”

It determines the smallest number of changes required and efficiently updates just the relevant elements of the Real DOM. This strategy decreases the amount of expensive re-renders while improving overall performance. By reducing direct interactions with the Real DOM, the Virtual DOM enhances application performance and minimizes latency, resulting in better user experiences. This method is essential for frameworks like React, which use the Virtual DOM to effectively manage complex and dynamic UIs.

The Virtual DOM Object Example
Using React, the following is an illustration of a Virtual DOM object:

const virtualDOM = {
type: 'div',
props: {
id: 'container',
className: 'wrapper',
children: [
{
type: 'h1',
props: {
children: 'Hello, World!'
}
},
{
type: 'p',
props: {
children: 'This is an example of Virtual DOM.'
}
}
]
}
};

In this example:

• Type indicates the type of the HTML element (e.g., ‘div’, ‘h1’, ‘p’).
• Props include the element’s attributes, including id, className, and children.
• Children is a collection of kid components that enables nesting.

The Virtual DOM is an object that contains information about the UI and how it should look. This object is employed by React to determine the difference between the previous Virtual DOM and the current one, thus allowing React to apply minimal changes to the Real DOM.

How is Virtual DOM Faster than Real DOM

By minimizing its direct impact on the Real DOM, the Virtual DOM is faster than the Real DOM because it is a heavy process. In the virtual DOM vs real DOM comparison, instead of updating the entire Real DOM structure for a change, the Virtual DOM creates a lightweight copy of the UI in memory. When changes are made, they are applied to the Virtual DOM first, and then a process called ‘diffing’ compares it to the previous version, ensuring only the necessary updates are made to the Real DOM.

This approach discovers the slightest changes to be done and interacts only with those parts of the Real DOM. This strategy is effective since it reduces the number of reflows and repaints, increases the rendering speed, and boosts performance, especially targeting those applications where frequent changes are observed.

How Virtual DOM Helps React

React virtual DOM increases the performance and speed of React in terms of the way updates are processed. React.JS tutorial uses the Virtual DOM in-between instead of manipulating the Real DOM with every change or update. This is where a component is altered in its state or properties; React initially changes the virtual DOM. It then uses a “diffing” technique to compare the new Virtual DOM versus the prior version and determines the differences, or “diffs.”

They generate the least amount of change needed to keep Real DOM current. This selective update reduces the number of costly reflows and repaints, thus enhancing the page’s efficiency in terms of rendering. React effectively delivers enhanced performance and user interface fluidity despite the increasing complexity of the applications’ nature by managing updates and eradicating direct DOM interactions.

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Critical Concepts of Virtual DOM

Here are some essential principles of the Virtual DOM in React JS:

• Virtual Representation: The UI components are represented virtually in memory via the Virtual DOM. It has the same structure as the Real DOM but is lighter and easier to edit.
• Diffing Method: React employs a diffing method to compare the new Virtual DOM to the prior version. This algorithm recognizes changes and provides the most effective method for updating the Real DOM.
• Reconciliation: Reconciliation applies modifications made in the Virtual DOM to the Real DOM. React merely updates the altered areas of the Real DOM, minimizing reflows and repaints.
• Component-based Design: The Virtual DOM integrates with React components design. Each component has its own Virtual DOM, which makes updating and rendering more efficient.
• Batch Updates: React allows you to batch and apply many updates simultaneously. This minimizes the changes to the Real DOM, resulting in better speed.
• Declarative Syntax: React’s declarative syntax lets developers specify the required UI state. React manages the complexities of updating the Virtual DOM and Real DOM, making the development process more manageable.
• Efficient Changes: By reducing direct interactions with the Real DOM and focussing on essential changes, the Virtual DOM contributes to a high-performance and responsive user experience.

Differences Between Virtual DOM & Real DOM & Shadow DOM

Here's a comparison table that highlights the main distinctions between Virtual DOM, Real DOM, and Shadow DOM:

How is Virtual DOM Different from Shadow DOM

The Virtual DOM and Shadow DOM serve distinct functions in web development. The Virtual DOM is an abstraction broadly utilized in frameworks like React to improve updating and rendering. It keeps a lightweight, in-memory model of the UI, reducing direct interactions with the Real DOM by only updating the essential components.

In comparison, the Shadow DOM is a web standard that encapsulates HTML, CSS, and JavaScript. It enables developers to construct isolated components with custom styles and scripts that do not interact with the rest of the content. While the Virtual DOM improves efficiency by optimizing updates, the Shadow DOM increases modularity and reusability by encapsulating component-specific resources.

Is Shadow DOM the Same as Virtual DOM

No, the Shadow DOM is not identical to the Virtual DOM. The Shadow DOM is a web standard that encapsulates HTML, CSS, and JavaScript within a component, resulting in a different, isolated subtree that does not impact or is affected by the main page. It improves modularity and reusability by defining styles and scripts.

In comparison, the Virtual DOM is a programming paradigm utilized by frameworks like React to improve speed. It is a lightweight, in-memory clone of the Real DOM. Changes are initially made to the Virtual DOM; a diffing technique determines the fewest adjustments required for the Real DOM. The Virtual DOM focuses on speed enhancements, whereas the Shadow DOM prioritizes encapsulation and component separation.

Conclusion

Understanding the differences between the Real DOM, Virtual DOM, and Shadow DOM is critical for modern web development. The Real DOM, while simple, can be wasteful for sophisticated changes. The Virtual DOM improves speed by reducing direct interactions with the Real DOM via efficient diffing and reconciliation techniques. 

Meanwhile, the Shadow DOM offers encapsulation, allowing for modular and reusable components by segregating styles and scripts. By adequately exploiting these technologies, developers may create more efficient, maintainable, and scalable web apps that improve performance and user experience. Each technique has distinct advantages contributing to a thriving and dynamic online ecology. Learn more about React interview questions & answers.

FAQs

What are the advantages of using virtual DOM in React?

React’s Virtual DOM increases performance by reducing updates, effectively managing rendering, and growing application responsiveness.

What is the complete form of DOM?

The Document Object Model (DOM) is a programming interface for online pages that represents organized content.

Which language is DOM?

The DOM is not a programming language but rather a programming interface. It is used with languages such as JavaScript to interact with and change page structure in web development.

What are the two types of DOM?

The two basic types of DOM are real DOM and virtual DOM. The Real DOM is the live representation of the web page with which the browser interacts directly, updating and displaying information as necessary. In contrast, the Virtual DOM is an in-memory abstraction that technologies such as React use to improve speed.

Why DOM is used in JavaScript?

DOM is utilized in JavaScript to allow for dynamic modification of web pages. It enables JavaScript to read, edit, and interact with HTML elements, attributes, and content in real-time, making it possible to update, handle events, and add interactive features without refreshing the page.