introduction.md

title
Introduction

TanStack Virtual is a headless UI utility for virtualizing long lists of elements in JS/TS, React, Vue, Svelte, Solid, Lit, and Angular. It is not a component therefore does not ship with or render any markup or styles for you. While this requires a bit of markup and styles from you, you will retain 100% control over your styles, design and implementation.

The Virtualizer

At the heart of TanStack Virtual is the Virtualizer. Virtualizers can be oriented on either the vertical (default) or horizontal axes which makes it possible to achieve vertical, horizontal and even grid-like virtualization by combining the two axis configurations together.

Here is just a quick example of what it looks like to virtualize a long list within a div using TanStack Virtual in React:

import { useVirtualizer } from '@tanstack/react-virtual';

function App() {
  // The scrollable element for your list
  const parentRef = React.useRef(null)

  // The virtualizer
  const rowVirtualizer = useVirtualizer({
    count: 10000,
    getScrollElement: () => parentRef.current,
    estimateSize: () => 35,
  })

  return (
    <>
      {/* The scrollable element for your list */}
      <div
        ref={parentRef}
        style={{
          height: `400px`,
          overflow: 'auto', // Make it scroll!
        }}
      >
        {/* The large inner element to hold all of the items */}
        <div
          style={{
            height: `${rowVirtualizer.getTotalSize()}px`,
            width: '100%',
            position: 'relative',
          }}
        >
          {/* Only the visible items in the virtualizer, manually positioned to be in view */}
          {rowVirtualizer.getVirtualItems().map((virtualItem) => (
            <div
              key={virtualItem.key}
              style={{
                position: 'absolute',
                top: 0,
                left: 0,
                width: '100%',
                height: `${virtualItem.size}px`,
                transform: `translateY(${virtualItem.start}px)`,
              }}
            >
              Row {virtualItem.index}
            </div>
          ))}
        </div>
      </div>
    </>
  )
}

Let's dig into some more examples!