"When you are building a social feed, data grid, or chat UI, everything feels fine with 10 mock items. Then you connect a real API, render 50,000 rows with myList.map(...), and the browser locks up. The core problem is simple: you are asking the DOM to do too much work. Virtualization solves this by rendering only what the user can actually see. Instead of mounting 50,000 nodes, you render the 15-20 items that are visible in the viewport, plus a small buffer."
"TanStack Virtual provides the heavy lifting for this pattern. It is a modern, headless virtualization utility: it handles scroll math, size calculations, and item positioning, while you keep full control over markup and styles. In this article, you will build a high-performance, real-world livestream chat feed from scratch. The feed will: Render thousands of messages Support dynamic row heights (long vs. short messages) Load older history as you scroll upward (inverted infinite scroll)"
Rendering thousands of DOM nodes causes browsers to become unresponsive because the DOM is asked to manage excessive elements. Virtualization reduces work by mounting only the items visible in the viewport plus a small buffer, dramatically lowering element count and improving performance. TanStack Virtual is a headless utility that handles scroll math, size calculations, and item positioning while leaving markup and styling to the developer. The project setup uses React + TypeScript with Vite and installs @tanstack/react-virtual and @faker-js/faker. A fixed-height scroll container with overflow-y: auto is required for the virtualizer to know its viewport.
Read at LogRocket Blog
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