An in-memory representation of the DOM for optimizing UI updates
Core Idea: The Virtual DOM (VDOM) is a programming concept where a virtual representation of the UI is kept in memory and synced with the real DOM through a process called reconciliation, originally designed to minimize costly DOM manipulations.
Key Elements
- A lightweight JavaScript representation of the actual DOM
- Originally created to batch and minimize DOM operations
- Performs diffing between previous and current states
- Applies only necessary changes to the real DOM
Implementation Process
- Create an in-memory representation of the DOM
- When state changes, create a new virtual DOM representation
- Compare the new virtual DOM with the previous one (diffing)
- Calculate the minimum number of operations needed to update the real DOM
- Apply only those specific changes in a batch
Historical Context
- Gained popularity with React around 2013
- Addressed performance concerns during a time when DOM operations were more costly
- Was considered innovative for improving UI rendering performance
- Became a standard approach in many frontend frameworks
Current Understanding
- Now considered overhead by many developers, especially for complex applications
- Creates two copies of the DOM structure in memory
- Adds computational complexity for diffing algorithms
- May be less efficient than direct DOM manipulation with modern browsers
Frameworks Using VDOM
- React (primary popularizer)
- Vue.js (pre-Vapor)
- Preact
- Many other React-inspired libraries
Additional Connections
- Broader Context: Frontend Rendering Techniques (one approach among many)
- Applications: React Rendering Pipeline (practical implementation)
- See Also: Modern Frontend Rendering Approaches (alternative approaches)
References
- React Documentation - Reconciliation
- Vue.js Documentation - Virtual DOM
#frontend #javascript #rendering #webdevelopment
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