Package Exports

react-cool-virtual

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (react-cool-virtual) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

`🚧 Work in progress, most APIs are done. Not production ready yet, but you can try it!`

♻️
react-cool-virtual

A tiny React hook for rendering large datasets like a breeze.

Features

♻️ Renders millions of items with highly performant way, using DOM recycling.
🎣 Easy to use, based on React hook.
💅🏼 Apply styles without hassle, just few setups.
🧱 Supports fixed, variable, dynamic, and real-time resize heights/widths.
🖥 Supports RWD (responsive web design) for better UX.
🚚 Built-ins load more callback for you to deal with infinite scroll + skeleton screens.
🖱 Imperative scroll-to controls for offset, items, and alignment.
🛹 Out of the box smooth scrolling and the effect is DIY-able.
⛳ Provides isScrolling indicator to you for performance optimization or other purposes.
🗄️ Supports server-side rendering (SSR) for faster FCP and better SEO.
📜 Supports TypeScript type definition.
🎛 Super flexible API design, built with DX in mind.
🦔 Tiny size (~ 2.8kB gzipped). No external dependencies, aside for the react.

Why?

When rendering a large set of data (e.g. list, table etc.) in React, we all face performance/memory troubles. There're some great libraries already available but most of them are component-based solutions that provide well-defineded way of using but increase a lot of bundle size. However a library comes out as a hook-based solution that is flexible and headless but applying styles for using it can be verbose. Furthermore, it lacks many of the useful features.

React Cool Virtual is a tiny React hook that gives you a better DX and modern way for virtualizing a large amount of data without struggle 🤯.

Docs

Frequently viewed docs:

Getting Started
Examples
API
Performance Optimization
Working in TypeScript
Sharing A ref
Polyfill

Getting Started

To use React Cool Virtual, you must use react@16.8.0 or greater which includes hooks.

Installation

This package is distributed via npm.

$ yarn add react-cool-virtual
# or
$ npm install --save react-cool-virtual

⚠️ This package using ResizeObserver API under the hook. Most modern browsers support it natively, you can also add polyfill for full browser support.

CDN

If you're not using a module bundler or package manager. We also provide a UMD build which is available over the unpkg.com CDN. Simply use a <script> tag to add it after React CND links as below:

<script crossorigin src="https://unpkg.com/react/umd/react.production.min.js"></script>
<script crossorigin src="https://unpkg.com/react-dom/umd/react-dom.production.min.js"></script>
<!-- react-cool-virtual comes here -->
<script crossorigin src="https://unpkg.com/react-cool-virtual/dist/index.umd.production.min.js"></script>

Once you've added this you will have access to the window.ReactCoolVirtual.useVirtual variable.

Basic Usage

Here's the basic concept of how it rocks:

import useVirtual from "react-cool-virtual";

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 10000, // Provide the total number for the list items
    itemSize: 50, // The size of each item (default = 50)
  });

  return (
    <div
      ref={outerRef} // Set the scroll container with the `outerRef`
      style={{ width: "300px", height: "500px", overflow: "auto" }}
    >
      {/* Set the inner element with the `innerRef` */}
      <div ref={innerRef}>
        {items.map(({ index, size }) => (
          // You can set the item's height with the `size` property
          <div key={index} style={{ height: `${size}px` }}>
            ⭐️ {index}
          </div>
        ))}
      </div>
    </div>
  );
};

✨ Pretty easy right? React Cool Virtual is more powerful than you think. Let's explore more use cases through the examples!

Examples

Some of the common use cases that React Cool Virtual can help you out.

Fixed Size

This example demonstrates how to create a fixed size row. For column or grid, please refer to CodeSandbox.

import useVirtual from "react-cool-virtual";

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 1000,
  });

  return (
    <div
      style={{ width: "300px", height: "300px", overflow: "auto" }}
      ref={outerRef}
    >
      <div ref={innerRef}>
        {items.map(({ index, size }) => (
          <div key={index} style={{ height: `${size}px` }}>
            ⭐️ {index}
          </div>
        ))}
      </div>
    </div>
  );
};

Variable Size

This example demonstrates how to create a variable size row. For column or grid, please refer to CodeSandbox.

import useVirtual from "react-cool-virtual";

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 1000,
    itemSize: (idx) => (idx % 2 ? 100 : 50),
  });

  return (
    <div
      style={{ width: "300px", height: "300px", overflow: "auto" }}
      ref={outerRef}
    >
      <div ref={innerRef}>
        {items.map(({ index, size }) => (
          <div key={index} style={{ height: `${size}px` }}>
            ⭐️ {index}
          </div>
        ))}
      </div>
    </div>
  );
};

Dynamic Size

This example demonstrates how to create a dynamic (unknown) size row. For column or grid, please refer to CodeSandbox.

import useVirtual from "react-cool-virtual";

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 1000,
    itemSize: 75, // The unmeasured item sizes will refer to this value (default = 50)
  });

  return (
    <div
      style={{ width: "300px", height: "300px", overflow: "auto" }}
      ref={outerRef}
    >
      <div ref={innerRef}>
        {items.map(({ index, measureRef }) => (
          // Use the `measureRef` to measure the item size
          <div key={index} ref={measureRef}>
            {/* Some data... */}
          </div>
        ))}
      </div>
    </div>
  );
};

💡 Scrollbar thumb is jumping? It's because the total size of the items is gradually corrected along with an item has been measured. You can tweak the itemSize to reduce the phenomenon.

Real-time Resize

This example demonstrates how to create a real-time resize row (e.g. accordion, collapse etc.). For column or grid, please refer to CodeSandbox.

import { useState, forwardRef } from "react";
import useVirtual from "react-cool-virtual";

const Item = forwardRef(({ children, height, ...rest }, ref) => {
  const [h, setH] = useState(height);

  return (
    <div
      {...rest}
      style={{ height: `${h}px` }}
      ref={ref}
      onClick={() => setH((prevH) => (prevH === 50 ? 100 : 50))}
    >
      {children}
    </div>
  );
});

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 50,
  });

  return (
    <div
      style={{ width: "300px", height: "300px", overflow: "auto" }}
      ref={outerRef}
    >
      <div ref={innerRef}>
        {items.map(({ index, size, measureRef }) => (
          // Use the `measureRef` to measure the item size
          <AccordionItem key={index} height={size} ref={measureRef}>
            👋🏻 Click Me
          </AccordionItem>
        ))}
      </div>
    </div>
  );
};

Responsive Web Design (RWD)

This example demonstrates how to create a list with RWD to provide a better UX for the user.

import useVirtual from "react-cool-virtual";

const List = () => {
  const { outerRef, innerRef, items } = useVirtual({
    itemCount: 1000,
    // Use the outer's width (2nd parameter) to adjust the item's size
    itemSize: (_, width) => (width > 400 ? 50 : 100),
    // The event will be triggered on outer's size is being changed
    onResize: (rect) => console.log("Outer's rect: ", rect),
  });

  return (
    <div
      style={{ width: "300px", height: "400px", overflow: "auto" }}
      ref={outerRef}
    >
      <div ref={innerRef}>
        {/* We can also access the outer's width here */}
        {items.map(({ index, size, width }) => (
          <div key={index} style={{ height: `${size}px` }}>
            📏 {width}
          </div>
        ))}
      </div>
    </div>
  );
};

Scroll to Offset/Items

You can imperatively scroll to offset or items as follows:

const { scrollTo, scrollToItem } = useVirtual();

const scrollToOffset = () => {
  // Scroll to 500px
  scrollTo(500, () => {
    // 🤙🏼 Do whatever you want through the callback
  });
};

const scrollToItem = () => {
  // Scroll to the 500th item
  scrollToItem(500, () => {
    // 🤙🏼 Do whatever you want through the callback
  });

  // Control the alignment of the item with the `align` option
  // Available values: "auto" (default) | "start" | "center" | "end"
  scrollToItem({ index: 500, align: "center" });
};

Smooth Scrolling

React Cool Virtual provides the smooth scrolling feature out of the box, all you need to do is turn the smooth option on.

const { scrollTo, scrollToItem } = useVirtual();

// Smoothly scroll to 500px
const scrollToOffset = () => scrollTo({ offset: 500, smooth: true });

// Smoothly scroll to the 500th item
const scrollToItem = () => scrollToItem({ index: 500, smooth: true });

The default easing effect is easeInOutCubic, and the duration is 500 milliseconds. You can easily customize your own effect as follows:

const { scrollTo } = useVirtual({
  // For 500 milliseconds (default = 500ms)
  scrollDuration: 500,
  // Using "easeInOutBack" effect (default = easeInOutCubic)
  // See: https://easings.net/#easeInOutBack
  scrollEasingFunction: (t) => {
    const c1 = 1.70158;
    const c2 = c1 * 1.525;

    return t < 0.5
      ? (Math.pow(2 * t, 2) * ((c2 + 1) * 2 * t - c2)) / 2
      : (Math.pow(2 * t - 2, 2) * ((c2 + 1) * (t * 2 - 2) + c2) + 2) / 2;
  },
});

const scrollToOffset = () => scrollTo({ offset: 500, smooth: true });

💡 For more cool easing effects, please check it out.

Infinite Scroll

Coming soon...

Dealing with Dynamic Items

Coming soon...

Server-side Rendering (SSR)

Coming soon...

Performance Optimization

Coming soon...

How to Share A `ref`?

You can share a ref as follows, here we take the outerRef as the example:

import { useRef } from "react";
import useVirtual from "react-cool-virtual";

const App = () => {
  const ref = useRef();
  const { outerRef } = useVirtual();

  return (
    <div
      ref={(el) => {
        outerRef.current = el; // Set the element to the `outerRef`
        ref.current = el; // Share the element for other purposes
      }}
    />
  );
};

Working in TypeScript

React Cool Virtual is built with TypeScript, you can tell the hook what type of your outer and inner elements are as follows:

const App = () => {
  // 1st is the `outerRef`, 2nd is the `innerRef`
  const { outerRef, innerRef } = useVirtual<HTMLDivElement, HTMLDivElement>();

  return (
    <div ref={outerRef}>
      <div ref={innerRef}>{/* Rendering items... */}</div>
    </div>
  );
};

💡 For more available types, please check it out.

API

Coming soon...

ResizeObserver Polyfill

ResizeObserver has good support amongst browsers, but it's not universal. You'll need to use polyfill for browsers that don't support it. Polyfills is something you should do consciously at the application level. Therefore React Cool Virtual doesn't include it.

We recommend using @juggle/resize-observer:

$ yarn add @juggle/resize-observer
# or
$ npm install --save @juggle/resize-observer

Then pollute the window object:

import { ResizeObserver } from "@juggle/resize-observer";

if (!("ResizeObserver" in window)) window.ResizeObserver = ResizeObserver;

You could use dynamic imports to only load the file when the polyfill is required:

(async () => {
  if (!("ResizeObserver" in window)) {
    const module = await import("@juggle/resize-observer");
    window.ResizeObserver = module.ResizeObserver;
  }
})();

To Do...

Unit testing
Reverse scrolling
Infinite loop
scrollBy method

Contributors ✨

Thanks goes to these wonderful people (emoji key):

_Welly
🤔 💻 📖 🚇 🚧

This project follows the all-contributors specification. Contributions of any kind welcome!