List Virtualization in React with TanStack Virtual

Anton Ioffe - March 22nd 2024 - 9 minutes read

In the rapidly evolving landscape of web development, React developers are constantly seeking methods to enhance application performance and user experience, especially when managing extensive datasets. Enter the world of list virtualization through the lens of TanStack Virtual, a cutting-edge library that is redefining how we handle large lists and grids with unmatched efficiency. Our journey will take us from foundational setups to mastering advanced list management techniques, delve into optimizing performance and memory usage, and navigate the common pitfalls to secure a seamless user journey. Whether you're looking to adopt list virtualization or refine your existing implementations, this article promises to equip you with the knowledge and skills to leverage TanStack Virtual in crafting highly responsive and efficient React applications. Prepare to transform your approach to handling massive datasets with insights tailored for the seasoned developer.

Understanding List Virtualization and The Role of TanStack Virtual

List virtualization represents a transformative optimization technique within web development, particularly when it comes to managing extensive datasets in React applications. At its core, list virtualization involves rendering only those items that are currently visible to the user within the viewport, rather than loading and displaying an entire dataset all at once. This methodology dramatically decreases the number of DOM elements that need to be created, managed, and manipulated, thereby significantly reducing the computational load. As a result, applications benefit from faster rendering times and improved overall performance, providing a smoother and more responsive user experience even when dealing with large lists or grids.

TanStack Virtual emerges as a potent library designed to leverage list virtualization effectively within React projects. It specializes in rendering only the items necessary based on the user's current scroll position. By doing so, TanStack Virtual ensures that applications remain agile and responsive, regardless of the dataset's size. This is particularly valuable in scenarios where rendering thousands or even millions of items could lead to severe performance degradation. With TanStack Virtual, developers have a robust tool at their disposal that can intelligently manage data rendering, tailoring the user experience to focus on what's currently visible — and relevant.

Understanding the significance of list virtualization and the role of TanStack Virtual begins with recognizing the challenges associated with managing large datasets. Traditional rendering approaches, where every item in a dataset is rendered simultaneously, can lead to an overwhelming strain on the browser's DOM, resulting in sluggish performance and unresponsive interfaces. This not only detracts from the user experience but can also pose significant barriers to scaling applications effectively. List virtualization addresses these challenges head-on, offering a proactive solution that prioritizes performance without sacrificing data access or visibility.

TanStack Virtual's approach to list virtualization is built around the concept of virtualized item rendering plus a small buffer area around the viewport. This buffer ensures that as the user scrolls through the data, new items are rendered just before they become visible, maintaining the illusion of a seamlessly endless list without the performance penalties associated with rendering the entire dataset upfront. The library provides developers with fine-grained control over how items are measured and rendered, allowing for customized implementations that fit the specific requirements of their applications.

In summary, list virtualization, facilitated by libraries like TanStack Virtual, plays a pivotal role in modern web development for React applications. It addresses the crucial need for efficient data handling and rendering in applications dealing with large datasets, ensuring that performance and user experience are not compromised. By intelligently rendering only the items within the user's immediate view and managing resources more effectively, TanStack Virtual helps developers overcome common challenges associated with traditional rendering methods, setting a new standard for responsiveness and efficiency in data-rich applications.

Setting Up Your React Project with TanStack Virtual

To incorporate TanStack Virtual into your React project, start by installing the library. Utilize a package manager like npm or yarn, and execute the command npm i @tanstack/react-virtual@beta or yarn add @tanstack/react-virtual@beta in your terminal. It's critical at this stage to verify that the installed version is compatible with your project to prevent any integration issues, as the TanStack ecosystem periodically updates.

Following the installation, the initial step involves setting up a React component that will utilize the virtualization capabilities of TanStack Virtual. Import the useVirtual hook from @tanstack/react-virtual, alongside React and the useRef hook, which is essential for referencing the DOM element that encapsulates your list. This foundational setup is crucial for leveraging virtualization efficiently.

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

function VirtualList() {
    const parentRef = useRef(null);
    // Further configuration and usage of useVirtual will follow here

In the VirtualList component, you'll need to configure useVirtual by providing it with necessary parameters such as the size of your list and the parent DOM element's reference. The useVirtual hook then manages the rendering of your list items based on the current scroll position, significantly minimizing unnecessary DOM manipulation and thus enhancing performance.

Integrating TanStack Virtual adds a layer of complexity but offers substantial benefits, particularly for managing and rendering large datasets. As you move forward, understanding and customizing the behavior of the useVirtual hook according to your project's needs will be paramount. It's also essential to appreciate the importance of a well-structured setup to leverage the full potential of list virtualization with TanStack Virtual, paving the way for a more responsive and performance-optimized React application.

Advanced List Management Techniques

Building upon the foundation set by basic virtualization techniques, advanced list management using TanStack Virtual introduces the capability to dynamically size items. This means that items within a list can vary in size and the virtualization algorithm will seamlessly adjust to ensure optimal rendering and performance. To achieve this, developers must implement a mechanism to measure items either in advance or on-the-fly. For instance, rendering variable-sized items in a virtualized list could involve the use of an on-render measurement strategy, where item sizes are determined as they are rendered, and the virtualizer's cached measurements are updated accordingly.

const rowVirtualizer = useVirtual({
  size: items.length,
  estimateSize: useCallback((index) => sizes[index] || 50, [sizes]), // Default size or dynamic measurement

Handling infinite loading presents another layer of complexity, requiring developers to fetch more data as the user scrolls, creating the illusion of an endless list. TanStack Virtual simplifies this by providing hooks that can be used to detect when the user is nearing the end of the list, enabling asynchronous data fetching without interrupting the user experience. This integration ensures that as users scroll, new data loads seamlessly, maintaining the fluidity of scrolling operations.

const fetchMoreItems = async () => {
  if (isFetching || isEndOfList) return;
  const newItems = await fetchData(); // Your fetch logic here
  setItems((currentItems) => [...currentItems, ...newItems]);
useEffect(() => {
  const unsubscribe = rowVirtualizer.scrollSubscribe(({ virtualStart }) => {
    const loadThreshold = items.length - 10;
    if (virtualStart > loadThreshold) fetchMoreItems();
  return () => unsubscribe();
}, [rowVirtualizer, items, fetchMoreItems]);

Additionally, responding to list resizing events is crucial for maintaining layout consistency across various devices and window sizes. Developers can leverage TanStack Virtual's responsiveness to automatically adjust the virtualized list when the container's dimensions change. This ensures that item placement and load strategy adapt in real time to alterations in the viewable area, preserving user interface integrity and interaction quality.

Optimizing for dynamic content and varying user interfaces often involves configuring custom scroll behaviors. TanStack Virtual allows for the customization of scroll properties, such as the overscan count—how many items to render outside of the viewport to prevent visual popping during fast scrolls. This, combined with customized loading strategies and responsive design adaptations, results in an ultra-smooth scrolling experience that can handle both predictable static heights and unpredictably dynamic content sizes.

By amalgamating these advanced techniques, developers can employ TanStack Virtual to manage complex list virtualization scenarios effectively. The key lies in understanding the nuances of asynchronous data fetching, dynamic item sizing, and responsive layout adjustments. When properly implemented, these strategies ensure that virtual lists remain smooth, responsive, and engaging for users, regardless of the underlying complexity or dataset size.

Optimizing Performance and Memory Usage

In the realm of optimizing virtualized lists within React applications, the judicious use of memoization stands out as a cornerstone strategy. By employing the useMemo and useCallback hooks, developers can significantly reduce the number of unnecessary renders, thereby conserving memory and enhancing performance. These hooks allow for the caching of expensive function results and the preservation of referential equality across re-renders for functions and variables, respectively. This is particularly crucial in scenarios involving the rendering of large datasets, where the computational overhead can be daunting. Here's an illustrative code snippet demonstrating the use of useMemo for memoizing a computationally heavy operation:

const expensiveList = useMemo(() => computeExpensiveValue(list), [list]);

This approach ensures that computeExpensiveValue is only executed when the list dependency changes, thereby avoiding needless computation and memory usage.

Another pivotal aspect of optimizing performance in virtualized lists involves efficient state and props management. Ensuring that components re-render only when necessary is key. This can be achieved by leveraging React.memo for functional components, which prevents re-renders unless prop values have changed. However, developers must exercise caution with the dependencies array of hooks like useEffect, useMemo, and useCallback, ensuring it accurately reflects all variables and props the effect depends on. Overlooking dependencies can lead to stale data or excessive re-renders, negating the performance benefits sought through memoization.

Understanding and utilizing the internals of the TanStack Virtual library is paramount for avoiding common pitfalls. For instance, correctly implementing dynamic item size measurement is essential for maintaining smooth scroll performance in lists where item sizes can vary significantly. This involves accurately updating the virtualizer's state with the measured sizes of rendered items, ensuring the virtual space calculation remains correct. Failure to do so can result in jumpy scroll behavior and inconsistent rendering, factors that detrimentally affect user experience.

Efficiently handling asynchronous data fetching within virtualized lists is another area where performance can be optimized. Strategies such as smart caching of fetched data and debouncing or throttling state updates related to data fetching can prevent unnecessary re-renders. Moreover, integrating these strategies with the virtualized list's scrolling and loading mechanism ensures that users experience a smooth and responsive interface even as new data is fetched and rendered. Here's a brief example of employing debouncing in the context of infinite loading:

function useDebouncedFetch(query, delay) {
  const [data, setData] = useState([]);
  useEffect(() => {
    const handler = setTimeout(() => fetchData(query).then(setData), delay);
    return () => clearTimeout(handler);
  }, [query, delay]);
  return data;

Optimization efforts must strike a balance between functionality and performance. Developers are challenged to thoughtfully apply memoization, manage state and prop updates efficiently, and delve deeply into the TanStack Virtual library's mechanics. The goal is to achieve high-efficiency virtualized lists that do not compromise on usability or responsiveness. Balancing the complexity introduced by features such as dynamic content measurement against their performance impact is vital. This delicate balance underscores the significance of adopting a performance-oriented mindset throughout the development process, ensuring that virtualized lists effectively cater to the needs of modern, dynamic React applications.

Common Mistakes and How to Avoid Them

One common mistake when implementing TanStack Virtual is the incorrect handling of variable-sized list items. Developers often assume a static size for all items, which can lead to improper item rendering and layout shifts. This mistake affects the smoothness of the scrolling and the accuracy of the items displayed.

// Incorrect
const itemSize = 50; // Assuming all items are of the same height
const rowVirtualizer = useVirtual({
  size: items.length,
  estimateSize: () => itemSize,

// Correct
const estimateSize = index => items[index].size || 50; // Dynamic size based on item
const rowVirtualizer = useVirtual({
  size: items.length,

Another prevalent issue is neglecting to memoize the estimateSize function, leading to unnecessary recalculations and degraded performance, especially with large datasets. Since function components re-render, not memoizing can cause expensive operations to run more often than needed.

// Incorrect
const estimateSize = index => expensiveSizeCalculation(items[index]);

// Correct
const estimateSize = useMemo(() => index => expensiveSizeCalculation(items[index]), [items]);

Mismanagement of asynchronous data fetching in conjunction with virtualization also poses significant challenges. Failing to correctly handle data fetching can result in incomplete lists, where users see loading indicators indefinitely without new items being rendered.

// Incorrect: Assuming data is immediately available upon fetching
useEffect(() => {
  fetchData().then(data => setItems(data));
}, []);

// Correct
useEffect(() => {
  fetchData().then(data => setItems(oldItems => [...oldItems,]));
}, [fetchData]);

Developers also frequently overlook the synchronization of scroll positions across multiple virtualized lists. Without careful management, users might experience inconsistent scroll states when interacting with lists intended to scroll in unison.

// Incorrect: Independent scrolls without synchronization
const list1Virtualizer = useVirtual({ size: list1.length, parentRef: list1Ref });
const list2Virtualizer = useVirtual({ size: list2.length, parentRef: list2Ref });

// Correct: Synchronizing scroll positions
const onScroll = e => {
  list1Ref.current.scrollTop =;
  list2Ref.current.scrollTop =;
const listVirtualizer = useVirtual({ size: list1.length, parentRef, onScroll });

Finally, not efficiently managing state and props in a virtualized environment can lead to redundant re-renders, hindering performance. Utilizing React's memoization hooks and carefully structuring components is essential.

// Incorrect: Passing un-memoized props, causing unnecessary re-renders
<List items={items} />

// Correct: Using React.memo and useMemo for props
const memoizedItems = useMemo(() => items, [items]);
<List items={memoizedItems} />

Reflecting on these common mistakes and their corrections should prompt a deeper exploration of TanStack Virtual’s documentation. By understanding and avoiding these pitfalls, developers can harness the full potential of list virtualization, ultimately creating more efficient and user-friendly React applications.


In this article, we explore the world of list virtualization in React with the TanStack Virtual library. List virtualization allows for efficient rendering of large datasets by only displaying the items that are currently visible to the user. TanStack Virtual takes this concept further by intelligently managing the rendering of items based on the user's scroll position. The article covers the setup process, advanced list management techniques, performance optimization, and common mistakes to avoid. A challenging task for readers is to implement the synchronization of scroll positions across multiple virtualized lists, ensuring a consistent user experience.

Don't Get Left Behind:
The Top 5 Career-Ending Mistakes Software Developers Make
FREE Cheat Sheet for Software Developers