Advanced Customization of Virtualized Lists Using TanStack Virtual in React Projects

Anton Ioffe - March 22nd 2024 - 10 minutes read

In the dynamic landscape of modern web development, customization and efficiency often stand as the twin pillars supporting successful React applications. With the advanced capabilities of TanStack Virtual, developers are poised to navigate the complexities of creating highly responsive and optimized interfaces. This article ventures deep into the realm of virtualization, unraveling the sophisticated strategies and innovative techniques that elevate virtualized lists and grids from merely functional to exceptionally performative. As we dissect the integration nuances, explore intricate customization avenues, uncover common pitfalls, and reveal the secrets behind a high-performance chat application, prepare to unlock a new horizon of possibilities with TanStack Virtual, harnessing its power to transform large datasets into smooth, engaging experiences. Join us on this enlightening journey, where theoretical knowledge meets practical wisdom, setting the stage for crafting cutting-edge React applications that stand the test of scale and user expectations.

Understanding Virtualization with TanStack Virtual

In the realm of React applications, managing large datasets efficiently poses a significant challenge, especially when it comes to rendering extensive lists or tables. This is where the concept of virtualization steps in, fundamentally changing how developers approach this issue. Virtualization, succinctly, involves rendering only the items that are visible to the user at any given moment. This technique drastically reduces the workload on the browser, ensuring smoother scroll performance and an overall enhanced user experience. TanStack Virtual emerges as a pivotal player in this domain, leveraging the virtualization concept to optimize performance and user experience in React projects. By intelligently rendering a subset of items from a larger list or dataset, it minimizes the resources required for DOM management and reduces the memory usage, addressing two critical web development challenges.

TanStack Virtual introduces a sophisticated mechanism known as the virtual window. This concept involves creating an invisible window through which only a portion of the list is rendered on the screen. As the user scrolls through the list, this window moves accordingly, creating the illusion that all items are rendered when, in fact, only a fraction is. This not only optimizes rendering performance but also significantly limits the amount of memory used. The virtual window ensures that only the items currently in the viewport plus a small buffer around it are rendered, thereby minimizing the number of DOM elements created and managed at any given time.

What sets TanStack Virtual apart in the sphere of virtualized lists and tables is its ingenious approach to handling the render cycle of items. It calculates the position and size of each item within the virtual window, efficiently updating the visible subset as the user scrolls. This dynamic rendering ensures that application responsiveness remains high, even when dealing with vast datasets. This approach contrasts sharply with traditional rendering methods, where the browser's performance can grind to a halt under the weight of thousands of DOM elements.

Beyond performance optimization, TanStack Virtual impresses with its contribution to enhancing the user experience. By maintaining smooth scrolling and quick load times, it prevents the jankiness and lag that often accompany the rendering of large lists using conventional methods. Users enjoy a seamless interaction with the application, unaware of the complex virtualization logic running behind the scenes. This improved user experience is crucial for applications requiring high levels of engagement and where performance could make or break user satisfaction.

The foundation of virtualization established by TanStack Virtual is essential for developers looking to dive deeper into advanced customization and optimization techniques in React projects. Understanding how TanStack Virtual manages a virtual window to efficiently render elements within the viewport while minimizing memory usage sets the stage for employing such technologies in complex projects. This nuanced approach to handling large datasets not only bolsters application performance but also enriches the end-user experience, making TanStack Virtual a formidable tool in the modern web developer's toolkit.

Integrating and Configuring TanStack Virtual

To integrate TanStack Virtual into a React project, start by installing the package with npm install @tanstack/react-virtual or yarn add @tanstack/react-virtual. This sets up your project with the necessary files. Following installation, create a React component where the virtualized list will be implemented. For beginners, handling a virtualized list with fixed-size items is a recommended starting point as it simplifies many of the variables involved.

With the package installed, the next step involves configuring the useVirtual hook within your React component. This setup requires importing useVirtual from @tanstack/react-virtual, as well as useRef from 'react', to reference the list container element. Establishing a container with a set or maximum height and overflow: auto CSS property is crucial, as it enables scrollable behavior which triggers the virtualization process. Here's a basic setup example:

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

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

    return (
            style={{ height: `150px`, overflow: 'auto' }}
            <div style={{ height: `${rowVirtualizer.totalSize}px`, width: '100%', position: 'relative' }}>
                { => (
                            position: 'absolute',
                            top: 0,
                            left: 0,
                            width: '100%',
                            height: `${virtualRow.size}px`,
                            transform: `translateY(${virtualRow.start}px)`
                        {`Row ${virtualRow.index}`}

In this example, useVirtual is configured with a basic set of parameters - primarily the size of the list (size) and a reference to the parent container (parentRef). This setup is sufficient for creating a simple virtualized list. However, tuning the performance of your virtualized lists requires delving into more intricate configurations of the useVirtual hook, such as adjusting item sizes and overscan. The overscan property dictates how many additional items are rendered outside of the visible area, preempting potential scroll delays and contributing to a smoother scrolling experience.

Understanding and configuring the useVirtual hook's parameters based on your project's needs can significantly affect performance. For example, if your list contains items of varying sizes, accounting for this variability ensures that the virtualized list behaves as expected, with items correctly assessed for their space requirements. This capability underscores TanStack Virtual's flexibility but also its complexity. Thus, refining the initial configuration—considering factors like dynamic item sizes, overscan settings, and event handling strategies—becomes pivotal in fully leveraging the library for optimal efficiency and smooth user experiences.

Advanced Customization Techniques

TanStack Virtual's robust architecture facilitates the creation of intricate layouts such as masonry or grid structures, specifically catering to those projects demanding dynamic item heights. Implementing such advanced layouts requires a keen understanding of how to dynamically adjust item sizes based on their content. Here's an example demonstrating the setup for a grid layout with variable item heights:

const gridVirtualizer = useVirtual({
  size: itemCount,
  estimateSize: useCallback(() => Math.floor(Math.random() * 150 + 75), []),
  useIsScrolling: true,

This code snippet initiates a grid with items of varying sizes, which is essential in creating responsive and visually appealing layouts. The estimateSize function plays a crucial role, dynamically setting each item's size, thus enabling the construction of complex grid patterns.

When addressing the theme of custom scrollbars, advanced customization comes into play to enhance both aesthetics and performance. Custom scroll containers allow for a unique user experience and can be tailored to match the application's design theme closely. To implement a custom scrollbar effectively, developers must wrap the virtualized list in a container with a custom scrollbar style, then manage the scroll events to synchronize with the virtualizer's state. Here's a brief glimpse into how this might look:

<div className='custom-scrollbar' ref={parentRef}>
  { => (
    <MyItemComponent key={virtualItem.key} item={items[virtualItem.index]} />

The container's class, custom-scrollbar, applies the custom scrollbar styling. Meanwhile, the virtualized items are rendered based on the state managed by TanStack Virtual, ensuring smooth scrolling and a cohesive look.

Optimizing scroll performance extends beyond mere aesthetics, touching upon the efficiency of event handling and data fetching. In scenarios with extensive data sets, managing scroll events through debouncing or throttling can drastically improve responsiveness. Efficient data fetching, on the other hand, can be achieved by intelligently loading data in chunks based on the user's scroll position, hereby reducing load times and improving the user's interaction with the application:

window.addEventListener('scroll', throttle(() => {
  if (window.scrollY + window.innerHeight >= document.documentElement.scrollHeight) {
}, 200));

This technique ensures that data fetching occurs only when necessary, significantly enhancing performance without disrupting the user experience.

Lastly, harnessing these advanced customization techniques demands a balanced approach. Developers must weigh the trade-offs between achieving optimal performance and maintaining a manageable codebase complexity. Thoughtful integration of these strategies, from handling dynamic item sizes to optimizing scroll performance, empowers developers to craft sophisticated, high-performance web applications. The nuanced application of these techniques can mean the difference between a good user experience and a great one. How might your current or upcoming projects benefit from these advanced customization practices within TanStack Virtual?

Overcoming Common Challenges and Debugging

Developing virtualized lists with TanStack Virtual brings inherent challenges, such as scroll flickering, state management issues, and the correct assignment of keys for dynamically changing content. Scroll flickering, often observed when dynamically loading data or adjusting item sizes, can significantly degrade user experience. A common mistake is overlooking the need for accurate measurement and state updating of item sizes. The correct approach involves utilizing a resize observer that dynamically adjusts the item sizes within the virtualizer's state, ensuring smooth recalibration of scroll positions.

State management issues often arise from improper synchronization between the virtual list and the application's state, especially in complex applications managing extensive datasets. A frequent oversight includes not properly handling the state updates, leading to inconsistent UI renders. Best practice dictates the use of shared state management solutions or React's context to maintain synchronization between the virtual list's state and the app's state, ensuring seamless UI updates and interaction.

Key management for dynamic content is another area prone to errors, particularly when developers reuse keys or do not assign them uniquely for list items. This can lead to erroneous re-renders or the incorrect ordering of list items. The solution is straightforward yet crucial: ensure that each list item has a unique key, possibly derived from the data's unique identifier, to maintain integrity and performance of the list rendering.

Monitoring memory usage and optimizing the rendering cycle are essential for maintaining high performance in virtualized lists. Developers should leverage browser debugging tools to observe and fine-tune the rendering process, identifying unnecessary re-renders or memory leaks. Techniques such as memoization of components and ensuring that callbacks are wrapped with useCallback can prevent unwanted re-renders, significantly reducing memory usage and enhancing performance.

Optimizing the rendering cycle further involves scrutinizing the list's interaction with user events, particularly scroll events. Implementing debouncing or throttling on scroll events can drastically reduce the frequency of recalculations and re-renders, smoothing out the scrolling experience. Moreover, developers should consider the implications of large datasets on the rendering cycle, implementing lazy loading techniques and virtualization to only render items in the viewport, further optimizing performance and resource consumption. By adhering to these best practices and debugging tips, developers can overcome common challenges, ensuring their virtualized lists are both efficient and robust.

Real-World Application: Building a High-Performance Chat Application

In the quest to build a high-performance chat application capable of handling an endless stream of real-time messages without sacrificing responsiveness or user experience, the adoption of TanStack Virtual emerged as a pivotal decision. The initial phase of the project underscored a critical need for efficient data handling and rendering, prompting a move towards virtualization. This choice was driven by the necessity to render only the messages in the user's viewport, significantly reducing the load on the browser and enhancing performance. The planning and decision-making process heavily leaned on leveraging TanStack Virtual's capabilities to manage the vast amount of data seamlessly.

Design considerations played a colossal role in achieving a smooth user experience. The interface was engineered to dynamically load and unload messages as users scrolled through their chat histories. This was adeptly managed through TanStack Virtual's hooks, granting the developers precise control over the rendering process based on the scroll position. These technical decisions were instrumental in consolidating the application’s user-friendliness, allowing for seamless navigation through extensive conversations without noticeable lag or performance issues.

One notable challenge encountered was the default scrolling behavior and rendering settings provided by TanStack Virtual. To surmount this, significant adjustments were made to the library's configurations to ensure smooth scrolling and immediate rendering of messages upon scroll. These optimizations included fine-tuning the overscan properties to pre-render messages just outside of the current viewport, reducing the perceptibility of loading times as users scrolled through their chats.

Customizing TanStack Virtual extended beyond scrolling optimizations. The project required dynamic measurement of message sizes due to the variable length of chat messages - a feature that TanStack Virtual accommodates but necessitates careful implementation. Utilizing the library’s functionality to estimate and adjust item sizes in real-time was paramount in handling messages of varying lengths gracefully. Alongside, memoization of chat message components was employed to minimize rerenders, further bolstering the application’s responsiveness.

This real-world application underscores TanStack Virtual's versatility and its profound impact on performance in demanding environments. Through meticulous customization and optimization, it was possible to fulfill the project's ambitious requirements, setting a new benchmark for what can be achieved in terms of performance and user experience in web-based chat applications. The process highlighted not just the power of virtualization with TanStack Virtual but also the importance of a thoughtful approach to design and technical challenges when dealing with high-volume, real-time data.


In this article, we explore the advanced customization possibilities that TanStack Virtual offers for virtualized lists in React projects. We delve into the concepts of virtualization and the benefits it provides in terms of performance and user experience. The article guides developers through integrating and configuring TanStack Virtual, as well as implementing advanced customization techniques such as dynamic item sizes and custom scrollbars. It also covers common challenges and debugging tips. The article concludes with a real-world example of building a high-performance chat application using TanStack Virtual. A challenging technical task for readers is to implement lazy loading techniques and optimize performance in their virtualized lists by rendering only the items in the viewport to improve responsiveness and resource consumption.

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