Frontend & browser·State, data and re-rendering
the list has fifty thousand rows and only the thirty on screen exist in the DOM at any moment.
List virtualisation
Also calledwindowing, virtual scrolling, virtualization
Rendering only the visible slice of a long list and adjusting the scroll container's height so the scrollbar still behaves. It is the only way to keep a large table interactive, because DOM node count drives layout, paint and memory. The costs are real: find-in-page, anchor links, keyboard navigation and screen readers all see only what is rendered, and variable row heights make the arithmetic considerably harder.