react-loading-skeleton/README.md

<div align="center">
    <a href="https://github.com/dvtng/react-loading-skeleton">
        <img src="assets/logo.svg" alt="Logo" width="80" height="80" />
    </a>
    <h1 align="center">React Loading Skeleton</h1>
    <p align="center">
        Make beautiful, animated loading skeletons that automatically adapt to your app.
    </p>
    <h3>
    <!--<a href="https://dvtng.github.io/react-loading-skeleton">View Live Demo</a> &nbsp;&nbsp;&bull;&nbsp;&nbsp;-->
    <a href="https://codesandbox.io/s/react-loading-skeleton-3xwil?file=/src/App.tsx">Open on CodeSandbox</a>
    </h3>
    <img src="https://media.giphy.com/media/l0Iyk4bAAjac3AU2k/giphy.gif" alt="Gif of the skeleton in action">
</div>

Learn about the [changes in version
3](https://github.com/dvtng/react-loading-skeleton/releases/tag/v3.0.0), or view
the [v2
documentation](https://github.com/dvtng/react-loading-skeleton/tree/v2#readme).

## Basic Usage

Install via one of:

```bash
yarn add react-loading-skeleton
npm install react-loading-skeleton
```

```tsx
import Skeleton from 'react-loading-skeleton'
import 'react-loading-skeleton/dist/skeleton.css'

<Skeleton /> // Simple, single-line loading skeleton
<Skeleton count={5} /> // Five-line loading skeleton
```

## Principles

### Adapts to the styles you have defined

The `Skeleton` component should be used directly in your components in place of
content that is loading. While other libraries require you to meticulously craft
a skeleton screen that matches the font size, line height, and margins of your
content, the `Skeleton` component is automatically sized to the correct
dimensions.

For example:

```tsx
function BlogPost(props) {
  return (
    <div>
      <h1>{props.title || <Skeleton />}</h1>
      {props.body || <Skeleton count={10} />}
    </div>
  );
}
```

...will produce correctly-sized skeletons for the heading and body without any
further configuration.

This ensures the loading state remains up-to-date with any changes
to your layout or typography.

### Don't make dedicated skeleton screens

Instead, make components with _built-in_ skeleton states.

This approach is beneficial because:

1. It keeps styles in sync.
2. Components should represent all possible states — loading included.
3. It allows for more flexible loading patterns. In the blog post example above,
   it's possible to have the title load before the body, while having both
   pieces of content show loading skeletons at the right time.

## Theming

Customize individual skeletons with props, or render a `SkeletonTheme` to style
all skeletons below it in the React hierarchy:

```tsx
import Skeleton, { SkeletonTheme } from 'react-loading-skeleton';

return (
  <SkeletonTheme baseColor="#202020" highlightColor="#444">
    <p>
      <Skeleton count={3} />
    </p>
  </SkeletonTheme>
);
```

## Props Reference

### `Skeleton` only

<table>
    <thead>
        <tr>
            <th>Prop</th>
            <th>Description</th>
            <th>Default</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code>count?: number</code></td>
            <td>
                The number of lines of skeletons to render. If
                <code>count</code> is a decimal number like 3.5,
                three full skeletons and one half-width skeleton will be
                rendered.
            </td>
            <td><code>1</code></td>
        </tr>
        <tr>
            <td><code>wrapper?: React.FunctionComponent <br> &lt;PropsWithChildren&lt;unknown&gt;&gt;</code></td>
            <td>
                A custom wrapper component that goes around the individual skeleton
                elements.
            </td>
            <td></td>
        </tr>
        <tr>
            <td><code>circle?: boolean</code></td>
            <td>
                Makes the skeleton circular by setting <code>border-radius</code> to
                <code>50%</code>.
            </td>
            <td><code>false</code></td>
        </tr>
        <tr>
            <td><code>className?: string</code></td>
            <td>
                A custom class name for the individual skeleton elements which is used
                alongside the default class, <code>react-loading-skeleton</code>.
            </td>
            <td></td>
        </tr>
        <tr>
            <td><code>containerClassName?: string</code></td>
            <td>
                A custom class name for the <code>&lt;span&gt;</code> that wraps the
                individual skeleton elements.
            </td>
            <td></td>
        </tr>
        <tr>
            <td><code>containerTestId?: string</code></td>
            <td>
                A string that is added to the container element as a
                <code>data-testid</code> attribute. Use it with
                <code>screen.getByTestId('...')</code> from React Testing Library.
            </td>
            <td></td>
        </tr>
        <tr>
            <td><code>style?: React.CSSProperties</code></td>
            <td>
                This is an escape hatch for advanced use cases and is not the preferred
                way to style the skeleton. Props (e.g. <code>width</code>,
                <code>borderRadius</code>) take priority over this style object.
            </td>
            <td></td>
        </tr>
    </tbody>
</table>

### `Skeleton` and `SkeletonTheme`

<table>
    <thead>
        <tr>
            <th>Prop</th>
            <th>Description</th>
            <th>Default</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code>baseColor?: string</code></td>
            <td>The background color of the skeleton.</td>
            <td><code>#ebebeb</code></td>
        </tr>
        <tr>
            <td><code>highlightColor?: string</code></td>
            <td>The highlight color in the skeleton animation.</td>
            <td><code>#f5f5f5</code></td>
        </tr>
        <tr>
            <td><code>width?: string | number</code></td>
            <td>The width of the skeleton.</td>
            <td><code>100%</code></td>
        </tr>
        <tr>
            <td><code>height?: string | number</code></td>
            <td>The height of each skeleton line.</td>
            <td>The font size</td>
        </tr>
        <tr>
            <td><code>borderRadius?: string | number</code></td>
            <td>The border radius of the skeleton.</td>
            <td><code>0.25rem</code></td>
        </tr>
        <tr>
            <td><code>inline?: boolean</code></td>
            <td>
                By default, a <code>&lt;br /&gt;</code> is inserted after each skeleton so
                that each skeleton gets its own line. When <code>inline</code> is true, no
                line breaks are inserted.
            </td>
            <td><code>false</code></td>
        </tr>
        <tr>
            <td><code>duration?: number</code></td>
            <td>The length of the animation in seconds.</td>
            <td><code>1.5</code></td>
        </tr>
        <tr>
            <td><code>direction?: 'ltr' | 'rtl'</code></td>
            <td>
                The direction of the animation, either left-to-right or right-to-left.
            </td>
            <td><code>'ltr'</code></td>
        </tr>
        <tr>
            <td><code>enableAnimation?: boolean</code></td>
            <td>
                Whether the animation should play. The skeleton will be a solid color when
                this is <code>false</code>. You could use this prop to stop the animation
                if an error occurs.
            </td>
            <td><code>true</code></td>
        </tr>
        <tr>
            <td><code>customHighlightBackground?: string</code></td>
            <td>
                Allows you to override the <code>background-image</code> property of the highlight element, enabling you to fully customize the gradient. See example below.
            </td>
            <td><code>undefined</code></td>
        </tr>
    </tbody>
</table>

## Examples

### Custom Wrapper

There are two ways to wrap a skeleton in a container:

```tsx
function Box({ children }: PropsWithChildren<unknown>) {
  return (
    <div
      style={{
        border: '1px solid #ccc',
        display: 'block',
        lineHeight: 2,
        padding: '1rem',
        marginBottom: '0.5rem',
        width: 100,
      }}
    >
      {children}
    </div>
  );
}

// Method 1: Use the wrapper prop
const wrapped1 = <Skeleton wrapper={Box} count={5} />;

// Method 2: Do it "the normal way"
const wrapped2 = (
  <Box>
    <Skeleton />
  </Box>
);
```

### Custom Highlight Background

You may want to make the gradient used in the highlight element narrower or wider. To do this, you can set the `customHighlightBackground` prop. Here's an example of a narrow highlight:

```tsx
<Skeleton customHighlightBackground="linear-gradient(90deg, var(--base-color) 40%, var(--highlight-color) 50%, var(--base-color) 60%)" />
```

**If you use this prop, the `baseColor` and `highlightColor` props are ignored,** but you can still reference their corresponding CSS variables as shown in the above example.

![Custom highlight background example](assets/custom-highlight-background.png)

## Troubleshooting

### The skeleton width is 0 when the parent has `display: flex`!

In the example below, the width of the skeleton will be 0:

```tsx
<div style={{ display: 'flex' }}>
  <Skeleton />
</div>
```

This happens because the skeleton has no intrinsic width. You can fix it by
applying `flex: 1` to the skeleton container via the `containerClassName` prop.

For example, if you are using Tailwind, your code would look like this:

```tsx
<div style={{ display: 'flex' }}>
  <Skeleton containerClassName="flex-1" />
</div>
```

### The height of my container is off by a few pixels!

In the example below, the height of the `<div>` will be slightly larger than 30
even though the `react-loading-skeleton` element is exactly 30px.

```tsx
<div>
  <Skeleton height={30} />
</div>
```

This is a consequence of how `line-height` works in CSS. If you need the `<div>`
to be exactly 30px tall, set its `line-height` to 1. [See
here](https://github.com/dvtng/react-loading-skeleton/issues/23#issuecomment-939231878)
for more details.

## Contributing

Contributions are welcome! See `CONTRIBUTING.md` to get started.

## Acknowledgements

Our logo is based off an image from [Font
Awesome](https://fontawesome.com/license/free). Thanks!