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How to Use React-Window: Best Tool for High-Performance Apps

What is the react window?

What is react window

React-Window is a paramount library in the realm of web development, celebrated for its lightweight and flexible solution to a common challenge many developers face: efficiently rendering large datasets in web applications. At its core, React Window is designed to enhance the performance and responsiveness of applications that handle extensive lists or complex tree structures, ensuring that users experience smooth interactions without the common lag associated with loading massive amounts of data.

React-Window is more than just a tool for improving web application performance; it’s a strategic solution that addresses the fundamental needs of modern web development. By reducing the over-allocation of resources and ensuring that data is just in time-loaded, React-Window aligns perfectly with the goals of developers and the expectations of users alike, marking it as a critical component in the toolkit of anyone looking to create highly efficient and user-friendly web applications.

Why Use React-Window?

why do developers usereact window?

React applications often grapple with the challenge of efficiently managing and rendering large datasets. As developers strive to create engaging and responsive user experiences, the ability to display extensive lists and complex tree structures without compromising performance becomes paramount. React-Window emerges as a specialized solution to these challenges, offering a streamlined approach to data rendering. Let’s break down the reasons to use React Window into focused subtopics:

Overcoming Performance Bottlenecks

  • The Challenge of Large Datasets: Rendering thousands of elements in a single view can overwhelm the browser’s DOM, leading to slow load times and sluggish interactions. This performance bottleneck is a common hurdle in developing responsive web applications.

  • Efficiency Through Virtualization: React Window optimizes rendering performance by implementing a virtualization technique. This method involves only rendering the DOM nodes of items that are currently in view, significantly reducing the memory footprint and improving application responsiveness.

Lightweight and Flexible Solution

  • Minimalistic Approach: React Window’s focused functionality on list and tree virtualization makes it a lightweight addition to projects, avoiding the overhead associated with more extensive libraries.

  • Adaptable to Various Use Cases: Whether dealing with fixed or variable item sizes, horizontal or vertical orientation, or even infinite loading scenarios, React Window provides the tools necessary to address a wide range of requirements with ease.

A Proven Solution for Large Data Rendering

  • Trusted by Developers: React-Window is widely adopted in the developer community for its effectiveness in handling large datasets without compromising on performance or user experience.

  • Success Stories: Numerous successful projects leverage React-Window to deliver high-performance applications, showcasing its reliability and the tangible benefits it offers.

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How React-Window Works

React Window employs a sophisticated yet straightforward technique known as “windowing” or “virtualization” to efficiently render large lists and tree structures in React applications. This approach dramatically improves performance by rendering only the items that are currently visible to the user, plus a small overhead to facilitate smooth scrolling. Let’s explore the technical implementation of React Window and provide some code examples to illustrate its basic setup and usage.

Technical Implementation

At its core, React-Window works by calculating which items should be visible based on the scroll position within a container. It then renders only those items, effectively minimizing the number of DOM nodes that need to be managed at any given time. This process involves dynamically adding and removing items from the DOM as the user scrolls, which significantly reduces memory usage and improves the responsiveness of the application.

React-Window provides two primary types of components for handling lists and grids: FixedSizeList and VariableSizeList for lists where the size of each item is known or varies, respectively. For grid layouts, it offers FixedSizeGrid and VariableSizeGrid. These components are designed to work seamlessly within the React ecosystem, allowing developers to integrate virtualization into their applications with minimal effort.

Basic Setup and Usage

To demonstrate how easy it is to get started with React-Window, let’s go through the setup of a basic FixedSizeList. This example will show how to render a simple list where each item has the same height.

First, ensure that you have React-Window installed in your project:

npm install react-window

Next, import FixedSizeList from React-Window and use it to render a list of items:

import React from 'react';
import { FixedSizeList as List } from 'react-window';

// Sample list items
const items = Array.from({ length: 1000 }, (_, index) => `Item ${index + 1}`);

// Row component
const Row = ({ index, style }) => (
  <div style={style}>

function App() {
  return (
      height={150} // Height of the list container
      itemCount={items.length} // Number of items in the list
      itemSize={35} // Height of each item
      width={300} // Width of the list container

export default App;

In this example, the FixedSizeList component is used to create a vertically scrollable list. The height and width props define the dimensions of the list container, while itemCount indicates the number of items in the list. The itemSize prop specifies the height of each item, allowing React Window to calculate which items need to be rendered as the user scrolls.

The Row component represents an individual item in the list. It receives index and style props from FixedSizeList. The index is used to access the corresponding item from the items array, and the style prop is used to position the item within the list correctly. This setup ensures that only the visible items (plus a small buffer) are rendered, significantly improving the performance of the application.

Comparing React-Window with Competitors

React Window and React Virtualized are two of the most prominent libraries used for optimizing the rendering of large lists and tree structures in React applications. Both libraries employ virtualization techniques to enhance performance, but they differ in their approach, features, and ease of use. To give a clearer picture of how React Window stands against its competitors, notably React Virtualized, let’s examine a comparative analysis focusing on key aspects such as performance, flexibility, and ease of use.

Comparison Table

FeatureReact WindowReact Virtualized
PerformanceHighly optimized for rendering large lists and grids with fewer features out-of-the-box, resulting in a smaller bundle size and potentially faster performance in simple use cases.Offers comprehensive features, including table support and dynamic cell measuring, which may introduce more complexity and a larger bundle size, potentially affecting performance.
FlexibilityDesigned to be a lightweight solution, providing the essential features needed for list and grid virtualization. It offers a more straightforward approach for common use cases.Provides a wide range of features and customization options, making it suitable for complex applications with diverse virtualization needs.
Ease of UseWith a minimalistic API, React Window is easier to learn and integrate into projects, making it an excellent choice for developers looking for a simple and efficient solution.Due to its extensive feature set, React Virtualized can have a steeper learning curve, but it offers more solutions for complex requirements out of the box.
Bundle SizeSmaller, resulting in faster load times for web applications.Larger, due to its more extensive feature set.
Use Case SuitabilityBest suited for applications that require straightforward list and grid virtualization without the need for advanced features such as dynamic cell sizing.Ideal for applications with complex virtualization needs, such as dynamic sizing and table virtualization, where the additional features justify the larger size.

Insights from LogRocket’s Blog Comparison

The comparison on LogRocket’s blog highlights several key advantages of React Window over React Virtualized, particularly in terms of bundle size and performance. React Window is designed as a more lightweight and focused library, making it particularly well-suited for applications that prioritize performance and have moderate virtualization needs. Its smaller footprint means less code to download and parse, which can significantly improve load times for web applications.

On the other hand, React Virtualized offers a broader set of features, catering to applications with complex virtualization requirements. This makes it a versatile tool, but it also means a larger bundle size and potentially more overhead for developers who only need basic virtualization capabilities.

Choosing between React Window and React Virtualized ultimately depends on the specific needs of your project. If you’re developing an application that requires the virtualization of large datasets but doesn’t need the extensive features offered by React Virtualized, React Window offers a performant, easy-to-use, and flexible solution. Its streamlined approach ensures that you can efficiently render large lists and grids, enhancing user experience without sacrificing performance. For more complex applications that demand advanced virtualization features, React Virtualized may be the better choice, despite the potential trade-offs in bundle size and initial learning curve.

Practical Use Cases of React Window

React Window also shines in scenarios where web applications need to render large amounts of data efficiently. Its ability to only render visible elements makes it an ideal solution for improving performance in various real-world applications. So here are some of the most common practical use cases where React Window can make a significant difference:

Large E-commerce Product Lists

In e-commerce platforms, displaying extensive product catalogs can be a challenge. Users expect quick access to a wide range of products without experiencing any lag or delay in loading times. React Window renders only the items in view as the user scrolls, ensuring smooth and responsive interactions. This approach not only enhances the user experience but also contributes to better SEO performance, as faster page load times are a ranking factor.

Example: An e-commerce site implemented React Window to handle their product grid, which contains over 10,000 items. By virtualizing the list, they reduced initial load times by 50% and improved scroll performance, leading to a noticeable increase in user engagement and conversion rates.

Long Data Tables

Applications that display data in tabular format, such as analytics dashboards, financial reports, or administrative interfaces, often deal with large datasets that can span thousands of rows. React Window can drastically improve the performance of these tables by rendering only the visible rows and dynamically loading additional data as the user scrolls. This ensures that even the most data-intensive tables remain responsive and easy to navigate.

Example: A financial analytics platform used React Window to optimize the rendering of stock market data tables. The tables, which previously took several seconds to load and often froze during scrolling, became instantly responsive, significantly enhancing the user experience for financial analysts.

Infinite Scrolling Feeds

Social media platforms, news aggregators, and content-heavy sites often use infinite scrolling to continuously load content as the user scrolls down. React Window integrates with infinite loading mechanisms to ensure that the growing list of content remains performant, providing a seamless browsing experience that keeps users engaged without overwhelming the browser.

Example: A popular blogging platform adopted React Window for their infinite scrolling feed, which features user-generated content including text, images, and videos. The implementation led to a 40% improvement in scroll performance and a significant reduction in memory usage, resulting in longer browsing sessions.

Implementing React Window in Your Project

Hpw to use react window in projects

Integrating React Window into your React project is a straightforward process that can yield significant performance improvements, especially for applications dealing with large datasets. This section will guide you through the steps to implement React Window, from installation to configuring a basic list or grid in your application.

Step 1: Installation

First, you need to add React Window to your project. If you’re using npm, you can install it with the following command:

npm install react-window

Alternatively, if you’re using yarn, use:

yarn add react-window

This command will download React Window and add it to your project’s dependencies.

Step 2: Choosing the Right Component

React Window provides several components for creating virtualized lists and grids:

  • FixedSizeList and VariableSizeList for lists where items have fixed or dynamic sizes, respectively.

  • FixedSizeGrid and VariableSizeGrid for grids with fixed or dynamic cell sizes.

Select the component that best fits your use case. For example, if you’re displaying a list where all items have the same size, FixedSizeList would be the most appropriate choice.

Step 3: Basic Setup for a List

Here’s how to set up a basic FixedSizeList:

import React from 'react';
import { FixedSizeList as List } from 'react-window';

const items = [...]; // Your list of items

const Row = ({ index, style }) => (
  <div style={style}>

const MyList = () => (
    height={500} // Height of the list container
    itemCount={items.length} // Number of items in the list
    itemSize={35} // Height of each item in pixels
    width="100%" // Width of the list container

export default MyList;

In this example, MyList is a React component that renders a list using FixedSizeList. Each row of the list is represented by the Row component, which receives its index and style from FixedSizeList for positioning.

Step 4: Customizing the Appearance

React Window allows you to attach custom properties and styles to your list or grid components. You can use the style prop to adjust the appearance of your list or individual items, ensuring that the virtualized components integrate seamlessly with the rest of your application’s design.

Step 5: Implementing Infinite Loading

To create an infinite loading list, you can combine React Window with an external library or your logic to fetch data as the user scrolls. Here’s a simplified example of how you might implement this:

import React, { useState, useEffect } from 'react';
import { FixedSizeList as List } from 'react-window';
import axios from 'axios'; // Assuming you're using axios for data fetching

const InfiniteLoaderList = () => {
  const [items, setItems] = useState([]);
  const [isFetching, setIsFetching] = useState(false);

  const fetchMoreItems = async () => {
    if (isFetching) return;
    const newItems = await axios.get('/api/items');
    setItems(prevItems => [...prevItems, ...newItems.data]);

  // Example logic for determining when to fetch more items
  // This can be refined based on your specific needs
  const onScroll = ({ scrollDirection, scrollOffset }) => {
    if (scrollDirection === 'forward' && scrollOffset > 0.9 * itemCount * itemSize) {

  return (

export default InfiniteLoaderList;

This example introduces a simple infinite loading mechanism by fetching more items when the user scrolls towards the end of the list

Advanced Techniques and Tips

While React Window simplifies the task of rendering large lists and tree structures, leveraging its full potential requires understanding some advanced techniques and best practices. Here are several tips and advanced methods that can help you maximize the efficiency and functionality of React Window in your projects:

Handling Dynamic Item Sizes

One of the challenges in virtualized lists is managing items with dynamic sizes, as React Window needs to know the size of an item to calculate which items are visible. For lists where items might not have a uniform size, you can use the VariableSizeList component, which allows for specifying a function that returns the size of an item given its index. Implementing this effectively requires careful management of item size calculations and possibly measuring the content in a non-virtualized context to determine the height dynamically.

import { VariableSizeList as List } from 'react-window';

const getItemSize = index => /* calculation or dynamic measurement */;


Efficiently Managing List Re-rendering

React Window components re-render only when the scroll position changes in a way to render necessary new items. However, if your item data changes or your component needs to respond to external state changes, you may need to implement a strategy to efficiently update the visible items. Thus, utilizing React’s context or hooks like useMemo and useCallback can help minimize unnecessary renders.

Integrating with React’s Context API

If your list or grid items need access to shared data, integrating React Window with React’s Context API allows you to pass down data without prop drilling. This is particularly useful for complex applications where list items might need access to global states or functions.

Using the outerRef and innerRef Props

React Window exposes outerRef and innerRef props that can be used to access the outer container and the inner element that holds the rendered items, respectively. These refs can be useful for implementing custom scrolling behaviors, measuring the scroll container, or integrating with other libraries.

Implementing Infinite Loading

React Window can be combined with infinite loading patterns to load data as the user scrolls. This involves detecting when the user has scrolled near the end of the list and then fetching more items. You can use the onItemsRendered prop to trigger load more data when certain rows come into view.

  onItemsRendered={({ visibleStartIndex, visibleStopIndex }) => {
    if (visibleStopIndex > data.length - threshold) {

Performance Optimization Tips

  • Avoid inline functions and objects in the renderer to prevent unnecessary re-renders.

  • Use memoization techniques to cache rendered items and avoid re-rendering items that haven’t changed.

  • When dealing with large datasets, consider strategies for lazy loading data or pre-fetching data before it becomes visible.

By mastering these advanced techniques and tips, you can further enhance the performance of your React applications using React Window. Whether it’s dealing with dynamic item sizes, integrating with other parts of the React ecosystem, or customizing the user experience, React Window offers the flexibility and efficiency needed for modern web development challenges.


As we’ve seen from various examples and success stories, React Window is not just a tool for performance optimization; it’s a pathway to creating more engaging and user-friendly web applications. Whether you’re a developer or just beginning your journey in web development, incorporating React Window into your projects can lead to substantial improvements in both performance and user satisfaction.

This approach not only addresses common performance bottlenecks but also meets the modern user’s expectations for swift and seamless digital experiences. Check out video resources to further advance knowledge here. However, in the spirit of modern expectations, Purecode’s AI tool brings in a solution for UI developers to generate production-quality markup by using images, screenshots, and designs with our AI code generator. Additionally, increases overall efficiency and automates end-to-end front-end code.Find out how now!!

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