Getting Started with React Virtuoso

React Virtuoso is a family of React components that display large data sets using virtualized rendering, automatically handling variable item sizes and changes in items' sizes.

Component	Purpose
Virtuoso	Flat lists
GroupedVirtuoso	Groups of items with sticky group headers
VirtuosoGrid	Same-sized items in a responsive grid layout
TableVirtuoso	Tables with virtualized rows
MessageList	Human/AI chat interfaces

info

Virtuoso Message List

The VirtuosoMessageList component is a newly released React component built specifically for human and AI chatbot conversations. Check out the live example.

License

The react-virtuoso package is distributed under the MIT license. The VirtuosoMessageList component and the contents of the @virtuoso.dev/message-list package are distributed under a commercial license. See pricing for more details.

Feature Highlights

The Virtuoso components automatically handle items with variable heights. You don't have to hard-code or manually measure item sizes. The components observe changes of the items' sizes (for example, due to content load) and automatically readjust the scroll area size. The component container size itself is observed and list readjusts its display automatically when the browser or its parent container changes sizes. You can safely use the Virtuoso components in responsive flexbox layouts.

A common use case covered by the components' API is the bi-directional endless scrolling and the press to load more UI patterns. The components can be configured to start from an initial location, thus skipping the initial rendering (and the potential need of data loading) of earlier items. The components expose startReached and endReached callback properties, suitable for loading data on demand. After the data has been loaded, You can append or prepend additional items, while retaining the current scroll location.

The markup of the components is customizable by passing custom components as props, supporting optional Header and Footer, or even replacing the Scroller element with a custom one (usually when integrating third party scrollbar library). The custom components props allow the easy integration of your UI library of choice (e.g. shadcn/ui, MUI, Mantine), or even integrate drag-and-drop through a third-party library.

To get a better impression of what's possible, examine the various examples in the documentation, and skim through the API reference.

Installation (react-virtuoso)

The Virtuoso components are distributed as NPM packages.

To use the Virtuoso, TableVirtuoso, GroupedVirtuoso, and VirtuosoGrid components, install react-virtuoso in your React project.

npm install react-virtuoso

Install the @virtuoso.dev/message-list package to use the VirtuosoMessageList component.

npm install @virtuoso.dev/message-list

Hello World

Virtuoso

Add the Virtuoso Component to your React project. The bare minimum it needs is a height for its container (either explicitly set, or adjusted through a parent flexbox), the number of items to display, and a callback to render the item content.

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VirtuosoMessageList

The Message List component is specifically built for human and/or AI chatbot conversations. Follow the instructions in the Virtuoso Message List guide to install and use the VirtuosoMessageList component.

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GroupedVirtuoso

The GroupedVirtuoso component is similar to the "flat" Virtuoso, with the following differences:

• Instead of totalCount, the Component accepts groupedCounts: number[], which specifies the amount of items in each group. For example, passing [20, 30] will render two groups with 20 and 30 items each;
• In addition the item render prop, the Component requires an additional group render prop, which renders the group header. The group callback receives the zero-based group index as a parameter;
• The itemContent render prop gets called with an additional second parameter, groupIndex: number.

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Check the grouped numbers, grouped by first letter and groups with load on demand examples.

TableVirtuoso

The TableVirtuoso component works like the Virtuoso one, but with HTML tables. It supports window scrolling, sticky headers, and fixed columns.

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VirtuosoGrid

The VirtuosoGrid component displays same sized items in multiple columns. The layout and item sizing is controlled CSS class properties or styled containers, which allows you to use media queries, min-width, percentage, etc.

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Performance

Several factors affect the component's performance. The first and most important one is the size of the visible area. Redrawing more items takes more time and reduces the frame rate. To see if this affects you, reduce the component width or height; Set the style property to something like {{width: '200px'}}.

Next, if the items are complex or slow to render, use React.memo for the itemContent contents.

// Item contents are cached properly with React.memo
const InnerItem = React.memo(({ index }) => {
  React.useEffect(() => {
    console.log('inner mounting', index)
    return () => {
      console.log('inner unmounting', index)
    }
  }, [index])
  return <div style={{ height: 30 }}>Item {index}</div>
})

// The callback is executed often - don't inline complex components in here.
const itemContent = (index) => {
  console.log('providing content', index)
  return <InnerItem index={index} />
}

const App = () => {
  return <Virtuoso totalCount={100} itemContent={itemContent} style={{ height: '100%' }} />
}

ReactDOM.render(<App />, document.getElementById('root'))

You can experiment with the increaseViewportBy property that specifies how much more to render in addition to the viewport's visible height. For example, if the component is 100px tall, setting the increaseViewportBy to 150 will cause the list to render at least 250px of content.

Loading images and displaying complex components while scrolling can cause jank. To fix that, you can hook to the isScrolling callback and replace the problematic content in the item with a simplified one. Check the scroll handling example for a possible implementation.

Caveats

Setting CSS margins to the content or the item elements is the Kryptonite of Virtuoso's content measuring mechanism - the contentRect measurement does not include them.

If this affects you, the total scroll height will be miscalculated, and the user won't be able to scroll all the way down to the list.

To avoid that, if you are putting paragraphs and headings inside the item, make sure that the top/bottom elements' margins do not protrude outside of the item container.

<Virtuoso
  totalCount={100}
  item={index => (
    <div>
      <p style={{ margin: 0 }}>Item {index}</p>
    </div>
  )}
/>

A few more common problems are present in the troubleshooting section.