React Under the Hood: Building a Tiny Virtual DOM Renderer

Short summary

Learn how virtual DOM-based UI frameworks like React work by building a minimal renderer from scratch. The article shows that the core concept—representing UI as JavaScript objects, comparing tree versions, and patching the real DOM—can be implemented in surprisingly few lines. Understanding this foundation reveals why new UI frameworks are quick to prototype on the web.

• •Virtual DOM renders UI as JavaScript objects and diffs them to minimize real DOM updates
• •A minimal React-like renderer can be built in ~30 lines, demonstrating low barriers to UI framework prototyping
• •JSX compiles to h() function calls; the patch() algorithm handles tree comparison and DOM patching

Generated with AI, which can make mistakes.