How to Virtualize a Long List in React Using TanStack Virtual for Better Performance

Anton Ioffe - March 21st 2024 - 11 minutes read

In the bustling world of modern web development, delivering seamless and efficient user experiences, especially when dealing with extensive datasets, has become paramount. Enter the realm of TanStack Virtual—a revolutionary library that redefines how long lists are managed and rendered in React applications. As we unravel the layers of this sophisticated tool, we'll embark on a comprehensive journey from its initial setup to mastering advanced virtualization techniques. Along the way, we'll confront common pitfalls, explore performance optimization strategies, and delve into best practices that promise to elevate your application's responsiveness to new heights. Whether you're looking to refine your approach to handling large volumes of data or eager to push the boundaries of what's possible with React, this article is tailored to guide senior-level developers through the nuances of leveraging TanStack Virtual for unparalleled performance gains.

The Essence of Virtualization with TanStack Virtual

TanStack Virtual represents a paradigm shift in how developers approach rendering extensive lists and tables in React applications. Its core philosophy revolves around the concept of virtualization—a technique that renders only the currently visible items in the viewport plus a small buffer. This starkly contrasts with traditional rendering methods, where every item in a list or table is rendered, regardless of its visibility. By adopting this virtualization strategy, TanStack Virtual drastically reduces the number of DOM elements that need to be managed at any given time, significantly improving both performance and user experience.

The significance of TanStack Virtual in modern web development cannot be overstated. In data-intensive applications, such as analytics dashboards or e-commerce platforms featuring thousands of product listings, ensuring a snappy user experience is paramount. Prior to the advent of virtualization techniques, rendering such massive datasets would severely degrade performance, leading to sluggish interfaces and, in extreme cases, browser crashes. TanStack Virtual mitigates these issues by ensuring that only a fraction of the total dataset is rendered and managed in the DOM, paving the way for applications that can effortlessly handle large volumes of data without compromising on speed or responsiveness.

At its heart, TanStack Virtual operates by tracking the scroll position within a container and calculating which items should be rendered based on their position relative to the viewport. This dynamic rendering ensures that as a user scrolls through a list, items entering the viewport are seamlessly rendered on-the-fly, while those leaving the viewport are removed from the DOM. This continuous cycle significantly reduces the memory footprint and enhances the overall performance of the application, as the number of elements in the DOM remains constant regardless of the size of the list or table being navigated.

Behind the scenes, TanStack Virtual employs an efficient algorithm to manage the elements within the virtualized list. It preemptively renders items just outside of the current viewport, ensuring that users experience smooth scrolling without any perceivable lag or jankiness. This buffering technique is a critical component of virtualization, as it strikes a balance between performance and user experience. Too small of a buffer could lead to frequent re-renders and a stuttering scroll, while too large a buffer negates the performance benefits of virtualization.

In conclusion, TanStack Virtual redefines the standards for rendering large datasets in React applications. By focusing on the items that are genuinely relevant to the user at any given moment, it delivers a high-performance, seamless experience that was previously challenging to achieve. This approach not only enhances application responsiveness but also contributes to a more efficient use of resources, ultimately benefiting both developers and users. Through the lens of virtualization, TanStack Virtual showcases the compelling advantages of rendering optimization, transforming the complexities of handling vast datasets into a manageable and performant endeavor.

Setting Up TanStack Virtual for List Virtualization

To embark on integrating TanStack Virtual into your React project for list virtualization, begin by ensuring the prerequisite package, @tanstack/react-virtual@beta, is installed. This can be achieved by executing npm i @tanstack/react-virtual@beta in your project’s terminal. It’s crucial to verify the version compatibility with your current setup to prevent potential integration issues, as the TanStack ecosystem is continuously evolving. This step is akin to incorporating any other external library into your React environment, laying the foundational stone for enhancing your application's performance through virtualization.

Following the successful installation, the next phase involves crafting a basic virtualized list component using TanStack Virtual. The cornerstone of this process is the useVirtual hook provided by the library, which is indispensable for tracking and rendering items based on the current scroll position. Begin by importing useVirtual from @tanstack/react-virtual, alongside React and useRef hooks, which are essential for accessing the DOM element that houses your list. This setup stage is critical as it establishes the initial configuration required to leverage virtualization effectively.

import { useVirtual } from '@tanstack/react-virtual';
import React, { useRef } from 'react';

function VirtualList() {
    const parentRef = useRef();
    const rowVirtualizer = useVirtual({
        size: 1000, // Total number of items
        parentRef, // Reference to the scrolling container

    return (
        <div ref={parentRef} style={{ height: `500px`, overflow: 'auto' }}>
            <div style={{ height: `${rowVirtualizer.totalSize}px`, position: 'relative' }}>
                { => (
                    <div key={virtualItem.index} style={{
                        position: 'absolute',
                        top: 0,
                        left: 0,
                        width: '100%',
                        height: `${virtualItem.size}px`,
                        transform: `translateY(${virtualItem.start}px)`
                        {`Item ${virtualItem.index}`}

In the outlined code, the useVirtual hook is initialized with a configuration object that specifies the total number of items (size) and a reference (parentRef) to the scrolling container. This initial setup illustrates the rendering of a simple, yet efficient, virtual list, highlighting the library's ability to manage a large set of items by only rendering those in the viewport. The example provided emphasizes the importance of defining a container's height and overflow properties to enable scrolling, which is crucial for the virtualization mechanism to operate.

Understanding the core API methods offered by TanStack Virtual is essential for harnessing its full potential in your React projects. For instance, rowVirtualizer.virtualItems returns an array of items currently available for rendering, including their position and size, which ensures that only visible items are rendered, significantly reducing the load on the browser's rendering engine. Moreover, rowVirtualizer.totalSize gives the total height of the virtualized items, facilitating the correct sizing of the container. This level of control and flexibility exemplifies why adopting TanStack Virtual can markedly improve the performance and user experience of applications dealing with extensive lists or datasets.

Through the integration and setup of a basic virtualized list as illustrated, developers can embark on utilizing TanStack Virtual to address and mitigate challenges associated with rendering large datasets. This initial foray not only boosts application performance but also familiarizes developers with virtualization concepts and the specific implementations within the TanStack Virtual library. As developers grow more comfortable with these foundational concepts, they can explore additional configurations and optimizations to further enhance their applications' efficiency and user engagement.

Advanced Techniques and Customizations

Implementing horizontal scrolling with TanStack Virtual becomes an essential consideration when dealing with extensive datasets that exceed the typical vertical display capacity. To achieve this, one must configure the horizontal property within TanStack Virtual's setup. However, adopting horizontal scrolling introduces challenges, particularly in CSS styling and user interaction, as most devices are optimized for vertical navigation. The nuanced complexity demands a carefully thought-out design to ensure usability does not suffer. Here's an example of enabling horizontal scrolling:

const rowVirtualizer = useVirtual({
  size: 1000, // Number of items
  parentRef, // Reference to the scrolling container
  horizontal: true, // Enable horizontal scrolling

Handling variable item heights presents another layer of complexity. Ensuring smooth performance and scrolling in a list with diverse item sizes requires a dynamic measurement system. TanStack Virtual accommodates this through the measureRef callback, used to capture and update the height of each item dynamically. This system promotes a responsive and fluid user experience but necessitates additional logic and state management to track item dimensions accurately.

const itemVirtualizer = useVirtual({
  size: items.length,
  estimateSize: useCallback(() => 50, []), // Initial size estimate
  measureRef, // Dynamically measures item sizes

Creating a virtual grid elevates the data presentation by organizing content both vertically and horizontally, suitable for applications such as image galleries or product listings. This setup requires managing two axes of virtualization simultaneously, increasing the setup complexity but providing a more immersive user interaction model. Configuring TanStack Virtual for grid functionality involves separate vertical and horizontal virtualizers, each responsible for a dimension of scrolling. The challenge lies in synchronizing these scrollings and ensuring the grid's performance across various devices.

Integrating custom scrollbars with TanStack Virtual allows developers to enhance the aesthetics and functionality of the scrolling interface. Custom scrollbars offer a unique opportunity to match the scrollbar design with the application's theme while improving the user experience. Implementing this requires intercepting the default scrolling behavior and rendering a custom scrollbar component that mirrors the scroll position and size of the virtualized content. Despite the clear benefits in user interface consistency and branding, this approach demands a deep understanding of browser scroll events and CSS styling to avoid disrupting the smooth scrolling experience facilitated by TanStack Virtual.

Each of these advanced customizations introduces a spectrum of trade-offs between performance, complexity, and user experience. The key to successful implementation lies in carefully evaluating the specific needs of your application against the potential impacts of these features. Advanced customizations like horizontal scrolling, variable item heights, virtual grids, and custom scrollbars push the boundaries of what's possible with TanStack Virtual, allowing developers to create highly optimized and user-centric web applications.

Common Mistakes and Their Solutions

One frequent oversight involves the handling of keys in virtualized lists, where developers might mistakenly use an array index as the key. This is particularly problematic due to the dynamic nature of virtual lists, where items can change positions, leading to potential performance issues and bugs. The solution lies in utilizing stable identifiers from your data as keys, ensuring React can precisely manage item updates and re-renders. For example:

// Incorrect key usage
{, index) => (
  <div key={index} style={}>...</div>
// Correct key usage
{ => (
  <div key={} style={}>...</div>

Another common pitfall is inadequate management of state and props, leading to unnecessary re-renders or stale data within virtualized lists. This can be mitigated by ensuring your virtual list components are pure and leveraging React's memoization techniques or libraries like React.memo for functional components to avoid rerendering when props or state haven’t changed. Additionally, proper handling of event handlers by debouncing or throttling can prevent excessive updates.

Mismanagement of dynamic content, such as failing to update the virtualizer's size when items are added or removed, poses another challenge. Developers should listen for changes in their data and update the virtualizer accordingly to ensure the UI accurately reflects the current state of the list. The useEffect hook is instrumental here, allowing you to synchronize the virtualizer's size with your data's actual size:

useEffect(() => {
  virtualRow.totalSize = calculateTotalSize(items);
}, [items]); // Dependency array includes items

Often overlooked are optimization opportunities, such as properly configuring the overscan count. While a high overscan count can preemptively load too many offscreen items, reducing application performance, a too-low count may result in noticeable loading artifacts during fast scrolling. Finding a balance based on your specific use case and testing performance across devices is essential:

const virtualRow = useVirtual({
  size: items.length,
  overscan: 5, // Optimal overscan count varies

Lastly, developers sometimes neglect the impact of variable item heights, failing to measure and update the size of items dynamically, which can lead to incorrect item placement and scrolling issues. Implementing a measurement strategy using the measureRef callback provided by TanStack Virtual ensures items are measured correctly, leading to smooth scrolling and accurate item rendering:

// Assign measureRef to each item for dynamic size measurement
{ => (
  <div ref={virtualRow.measureRef} key={} style={}>...</div>

By addressing these common mistakes with the outlined solutions and code examples, developers can significantly improve the performance and reliability of virtualized lists in React applications, leading to better user experiences and more maintainable codebases.

Performance Optimization and Best Practices

Optimizing the performance of virtualized lists in React applications, especially when leveraging libraries like TanStack Virtual, requires a profound understanding of React's rendering mechanisms and efficient data handling strategies. The cornerstone of performance optimization in this context is memoization. By wrapping each list item component with React.memo, you ensure that React re-renders the item only if its props have changed. This is particularly crucial in large datasets where the overhead of rendering unnecessary updates can significantly dampen the scrolling smoothness and overall responsiveness. Consider this code snippet that demonstrates the use of memoization in a list item component:

const ListItem = React.memo(({ itemData }) => {
  return <div>{}</div>;

The concept of re-render optimization extends beyond memoization. Developers must be vigilant about the implications of frequent state updates that can trigger re-renders of the entire list. Using techniques like useMemo and useCallback hooks for complex calculations and functions passed as props can further minimize avoidable rendering operations. It's also essential to leverage the virtualizer.totalSize property accurately to ensure that the container size dynamically adjusts to the content, preventing unnecessary scroll adjustments and layout shifts.

Data fetching and rendering strategies in virtualized lists must also be thoroughly optimized. One common approach is to fetch large datasets in chunks and only load additional data as the user scrolls closer to the boundary of the currently loaded dataset. This lazy-loading strategy, combined with prefetching data just before it's needed, ensures that the user experiences a smooth scrolling experience without facing loading spinners frequently. Here’s how you might implement a basic intersection observer to trigger data fetching as the user approaches the end of the list:

const observer = new IntersectionObserver(entries => {
}, { threshold: 1.0 });


Scalability considerations are paramount when optimizing virtualized lists. Developers should ask themselves: How will the implementation fare with an order-of-magnitude increase in data size? Is the current data fetching and rendering strategy efficient and sustainable for future growth? These considerations ensure the virtualized list remains performant, even as the application scales.

Lastly, the developer community often overlooks the implications of dynamic content within virtualized lists — a factor that significantly affects performance. When list items can change size based on their content, it introduces complexity in accurately calculating the virtualized space. React developers should ensure their virtualizer library can dynamically adjust to content-driven dimension changes or implement custom logic to handle these updates seamlessly. Employing a dynamic measuring mechanism for list items, as shown in the following pseudo-code, is one approach to handling variable dimensions:

const measuredRef = useCallback(node => {
  if (node !== null) {
    updateItemSize(index, node.getBoundingClientRect().height);
}, []);

In summary, by carefully considering memoization, efficient data fetching, scalability, and the dynamic nature of content, developers can significantly optimize the performance of virtualized lists in React applications, ensuring a smooth and responsive user experience.


In this article, the author introduces TanStack Virtual, a revolutionary library for virtualizing long lists in React applications. They explain the concept of virtualization and how TanStack Virtual improves performance and user experience by rendering only the currently visible items. The article covers the setup process and provides code examples for creating a basic virtualized list. Advanced techniques such as horizontal scrolling, variable item heights, virtual grids, and custom scrollbars are also discussed, along with common mistakes and their solutions. The article concludes with performance optimization strategies, highlighting the importance of memoization, efficient data handling, and thoughtful data fetching and rendering strategies. The key takeaway is that by leveraging TanStack Virtual and implementing best practices, developers can create highly performant and user-friendly web applications.

Challenge: Implement lazy-loading and prefetching techniques to fetch and render large datasets in virtualized lists, ensuring a smooth scrolling experience for users without frequent loading spinners.

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