What is Virtual DOM in ReactJS? | Clear & Simple Explanation for Interviews | NareshIT

Summary

In this video, the concept of the Document Object Model (DOM) and its role in web development is explained. DOM is a hierarchical structure of elements that represent a webpage. However, ReactJS uses a 'virtual DOM,' which is a lightweight copy of the actual DOM, designed to enhance performance. When users interact with a webpage, changes are first made to the virtual DOM and then reflected in the actual DOM, making the user interface faster and more responsive. This allows React to efficiently render changes, offering a smoother user experience.

Takeaways

• 😀 DOM stands for Document Object Model, which is a hierarchy of elements in a webpage.
• 😀 Markup code is converted into bytes, then characters, and finally tokens through tokenization.
• 😀 Tokens (elements) are organized in a hierarchical structure known as the DOM.
• 😀 The browser's BOM (Browser Object Model) includes objects like window, location, history, and navigator, which interact with the DOM.
• 😀 The DOM represents all the elements, including images, forms, and applets, that make up the webpage.
• 😀 ReactJS uses a 'Virtual DOM' instead of directly interacting with the actual DOM.
• 😀 The Virtual DOM is a lightweight, in-memory representation of the actual DOM.
• 😀 Any changes made through interactions in React are first updated in the Virtual DOM for quicker feedback.
• 😀 The Virtual DOM allows for faster rendering, providing a more responsive user experience.
• 😀 After updates in the Virtual DOM, the changes are later synchronized with the actual DOM to reflect the final result.
• 😀 The use of the Virtual DOM enhances performance by making the interface more efficient and reducing rendering times.

Q & A

What is the DOM (Document Object Model)?

The DOM is a hierarchy of elements arranged on a web page. It represents the structure of a webpage, where developers write markup that gets translated into bytes, characters, and then tokens. These tokens are organized in a hierarchical order to form the DOM.

What does the DOM represent on a webpage?

The DOM represents the structure of the webpage's elements, such as images, forms, and other HTML elements. It organizes these elements in a tree-like hierarchy.

What is tokenization in the context of the DOM?

Tokenization is the process of converting characters into tokens. These tokens, or elements, are then arranged in a hierarchical order to form the DOM.

What is the BOM (Browser Object Model)?

The BOM (Browser Object Model) is a higher-level structure that represents the objects available in the browser environment. This includes objects like the window, location, history, navigator, and the document.

How does React handle the DOM differently from traditional web development?

Unlike traditional web development, React does not manipulate the DOM directly. Instead, it uses a Virtual DOM, which is a lightweight copy of the actual DOM stored in memory. React updates this virtual representation first and later reflects changes in the actual DOM.

What is the Virtual DOM in React?

The Virtual DOM is a lightweight, in-memory copy of the actual DOM. React uses it to update the user interface quickly, providing a faster experience by only updating the real DOM when necessary.

Why does React use the Virtual DOM?

React uses the Virtual DOM to improve performance. By updating the Virtual DOM first and then syncing it with the real DOM later, React can render changes faster and provide a more responsive user experience.

What happens when an update occurs in React’s Virtual DOM?

When an update occurs, React first modifies the Virtual DOM. The changes are then reflected in the actual DOM after the update is processed, which results in a faster user interface response time.

How does the Virtual DOM improve user experience?

The Virtual DOM enhances the user experience by offering faster rendering. Because updates occur in the Virtual DOM before affecting the actual DOM, the user sees changes more quickly without waiting for the full DOM manipulation process.

Is the Virtual DOM the same as the actual DOM?

No, the Virtual DOM is not the same as the actual DOM. It is a lightweight, in-memory version of the actual DOM that is used for quick updates. Changes made in the Virtual DOM are later reflected in the actual DOM.