Understanding Virtual DOM and Its Role in ReactJS
Title: The Virtual DOM: An In-depth Look at how React Utilizes it
The term ‘Virtual DOM’ is consistently used in discussions concerning the JavaScript library, React.js. When first-hand users are questioned about why they prefer React.js, one of the most common responses is ‘Virtual DOM’. To fully comprehend the React library’s profit and functionality, it’s necessary to understand what the Virtual DOM is and how React utilizes it.
What is a DOM?
Before explicating the Virtual DOM concept, let’s rewind a bit and first understand what DOM (Document Object Model) is. As suggested by its name, a DOM represents an object-oriented representation of a web page, which can be interacted with and manipulated. Essentially, it provides an interface with your HTML, SVG, and XML documents. It acts like a real-time schematic, allowing developers to add, modify, and delete HTML elements and attributes.
Nevertheless, it is vital to note that DOM manipulations are expensive in terms of performance. Furthermore, working with the DOM can become slow and arduous due to its tree-structured, recursive nature, which yields less efficient operations.
The Concept of Virtual DOM
The Virtual DOM is a concept brought about mainly by the introduction and popularity of React.js. Essentially, the Virtual DOM is a clone of the actual page’s DOM but lighter as it lacks the power to directly alter what appears on the screen.
Instead, it plays the role of a ‘virtual browser’ that is more friendly to developers. When changes are made to a web page, they first arrive at the Virtual DOM, which then computes the most efficient way to implement these changes in the least expensive way in the real DOM, consequently altering what the user sees on the screen.
This approach significantly minimizes the direct manipulation of the DOM, leading to a boost in the website’s performance and providing a faster and smoother user experience.
How Does React Utilize the Virtual DOM?
React’s use of the Virtual DOM is one of its trademarked features. Here is a simplified breakdown of how it operates:
- Creation of the Virtual DOM: When a component’s state changes within a React app, a new Virtual DOM representation of the user interface is created. This representation consists of React elements, which are objects – a snapshot of the user interface at a particular point in time.
- Comparison with the previous Virtual DOM: React then compares this newly created Virtual DOM with the former one (a process called ‘diffing’). In simple terms, React calculates the difference between the current Virtual DOM and the previous one.
- Update of the Real DOM: React then updates the real DOM efficiently, altering only those Objects in the real DOM that changed in the Virtual DOM during the ‘diffing’ process. This technique is termed ‘reconciliation’.
The whole process, from creating the Virtual DOM to updating the actual DOM, takes place remarkably swiftly that users don’t notice the behind-the-scenes operation.
React’s combination of the Virtual DOM concept and its reconciliation algorithm allows it to achieve fast and efficient updates in the real DOM. This process results in less direct manipulation of the real DOM, better app performance, better user experience, and significantly lower costs — features that all console developers should crave.
In summary, understanding the concept of the Virtual DOM and how React utilizes its power is key to appreciating and working effectively with the React library. So next time you create, debug, or use a React app, remember the Virtual DOM working seamlessly under the hood for your benefit.
