rehype-callouts/README.md

Rehype plugin for processing and rendering blockquote-based callouts (admonitions/alerts).

# rehype-callouts

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A [rehype](https://github.com/rehypejs/rehype) plugin for processing and rendering blockquote-based callouts.

## What is this?

This plugin adds support for callouts (admonitions/alerts), allowing you to use [Obsidian's callout syntax](https://help.obsidian.md/Editing+and+formatting/Callouts) to achieve the following features:

- Includes default callout types for various themes.
- Supports collapsible callouts with `-/+` and nestable callouts.
- Optionally import stylesheets for corresponding themes.
- Allows custom titles with markdown syntax.
- Customizable default callout types.
- Configurable new callout types.
- Configurable aliases for callout types.
- Configurable icon display.
- Configurable element attributes.

## When should I use this?

This plugin helps render markdown callouts, ideal for blogs built with frameworks like Astro or Next.js. It processes HTML directly without needing `allowDangerousHtml` in [remark-rehype](https://github.com/remarkjs/remark-rehype) and supports collapsible callouts with the `details` tag, all without JavaScript.

## Installation

This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c). In Node.js (version 18+), install with your package manager:

```sh
npm install rehype-callouts
yarn add rehype-callouts
pnpm add rehype-callouts
```

In Deno with [`esm.sh`](https://esm.sh/):

```js
import rehypeCallouts from 'https://esm.sh/rehype-callouts'
```

In browsers with [`esm.sh`](https://esm.sh/):

```html
<script type="module">
  import rehypeCallouts from 'https://esm.sh/rehype-callouts?bundle'
</script>
```

## Usage

Say `example.md` contains:

```md
<!-- Callout type names are case-insensitive: 'Note', 'NOTE', and 'note' are equivalent. -->

> [!note] This is a _non-collapsible_ callout
> Some content is displayed directly!

> [!WARNING]- This is a **collapsible** callout
> Some content shown after opening!
```

For vanilla JS：

```js
// example.js
import { unified } from 'unified'
import remarkParse from 'remark-parse'
import remarkRehype from 'remark-rehype'
import rehypeCallouts from 'rehype-callouts'
import rehypeStringify from 'rehype-stringify'
import { readSync } from 'to-vfile'

const file = unified()
  .use(remarkParse)
  .use(remarkRehype)
  .use(rehypeCallouts)
  .use(rehypeStringify)
  .processSync(readSync('example.md'))

console.log(String(file))
```

For Astro projects:

```ts
// astro.config.ts
import { defineConfig } from 'astro/config'
import rehypeCallouts from 'rehype-callouts'

// https://docs.astro.build/en/reference/configuration-reference/
export default defineConfig({
  markdown: {
    rehypePlugins: [rehypeCallouts],
  },
})
```

For Next.js projects:

```ts
// next.config.ts
import createMDX from '@next/mdx'
import rehypeCallouts from 'rehype-callouts'
import type { NextConfig } from 'next'

// https://nextjs.org/docs/app/api-reference/config/next-config-js
const nextConfig: NextConfig = {
  pageExtensions: ['js', 'jsx', 'md', 'mdx', 'ts', 'tsx'],
}

const withMDX = createMDX({
  options: {
    remarkPlugins: [],
    rehypePlugins: [rehypeCallouts],
    // With Turbopack, specify plugin names as strings
    // rehypePlugins: [['rehype-callouts']],
  },
})

export default withMDX(nextConfig)
```

Run `node example.js` (`pnpm dev`) to get:

```html
<div class="callout" data-callout="note" data-collapsible="false">
  <div class="callout-title">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <em>non-collapsible</em> callout
    </div>
  </div>
  <div class="callout-content">
    <p>Some content is displayed directly!</p>
  </div>
</div>

<details class="callout" data-callout="warning" data-collapsible="true">
  <summary class="callout-title">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <strong>collapsible</strong> callout
    </div>
    <div class="callout-fold-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
  </summary>
  <div class="callout-content">
    <p>Some content shown after opening!</p>
  </div>
</details>
```

## API

This package exports no identifiers. The default export is [`rehypeCallouts`](#unifieduserehypecallouts-options).

### `unified().use(rehypeCallouts[, options])`

Used to render callouts.

###### Parameters

- `options` ([`UserOptions`](#useroptions), optional) — configuration

###### Returns

Transform ([`Transformer`](https://github.com/unifiedjs/unified#transformer)).

### `UserOptions`

Configuration (TypeScript type). All options are optional.

###### Fields

- `theme` (`'github'|'obsidian'|'vitepress'`, default: `'obsidian'`) — your desired callout theme to automatically apply its default callout types.
- `callouts` ([`Record<string, CalloutConfig>`](https://github.com/lin-stephanie/rehype-callouts/blob/main/src/types.ts#L16), default: see [source code](https://github.com/lin-stephanie/rehype-callouts/tree/main/src/themes)) — define default or custom callouts as key-value pairs, where each key is a callout type and the value specifies its default text and icon, e.g., `{'note': {title: 'custom title'}, 'custom': {title: 'new callout', indicator: '<svg ...">...</svg>'}}`.
- `aliases` (`Record<string, string[]>`, default: `{}`) — aliases for callout types, e.g., `{'note': ['n'], 'tip': ['t']}`.
- `showIndicator` (`boolean`, default: `true`) — whether to display an type-specific icons before callout title.
- `tags` ([`TagsConfig`](https://github.com/lin-stephanie/rehype-callouts/blob/main/src/types.ts#L42), default: all `div`) — HTML tag names for callout structure elements.
- `props` ([`PropsConfig`](https://github.com/lin-stephanie/rehype-callouts/blob/main/src/types.ts#L103), default: all `null`) — properties for callout structure elements, where `class` or `className` overrides default class names; see [examples](#examples) below.

## Styling

You can customize callout styles with the class names or by importing the provided [theme-specific](#themes) stylesheets using one of the following methods.

Import in JavaScript/TypeScript:

```ts
import 'rehype-callouts/theme/github'
// import 'rehype-callouts/theme/obsidian'
// import 'rehype-callouts/theme/vitepress'
```

Import in a CSS file:

```css
@import 'rehype-callouts/theme/github';
```

Import in a Sass file:

```scss
@use 'rehype-callouts/theme/github';
```

Directly include in HTML via CDN ([unpkg.com](https://unpkg.com) or [jsdelivr.net](https://www.jsdelivr.com/)):

```html
<link
  rel="stylesheet"
  href="https://unpkg.com/rehype-callouts/dist/themes/github/index.css"
/>
<link
  rel="stylesheet"
  href="https://cdn.jsdelivr.net/npm/rehype-callouts/dist/themes/github/index.css"
/>
```

Once imported, you can set colors for default or custom callouts as follows:

```css
/* Using CSS custom properties (for default callouts only) */
:root {
  --callout-note-color-light: pink;
  --callout-note-color-dark: #ffc0cb;
  --callout-tip-color-light: rgb(255, 192, 203);
  --callout-tip-color-dark: hsl(350, 100%, 88%);
  /* Customize colors for default callout types included in the theme 
  using `--callout-{type}-color-{light|dark}: <color>` */
}

/* Using attribute selectors (for both default and custom callouts) */
/* Custom callouts default to `#888` if no color is set */
[data-callout='warning'],
[data-callout='custom'] {
  --rc-color-light: pink;
  --rc-color-dark: #ffc0cb;
}
```

### Themes

This package provides callout styles compatible with [GitHub](https://github.com/orgs/community/discussions/16925), [Obsidian](https://help.obsidian.md/Editing+and+formatting/Callouts), and [VitePress](https://vitepress.dev/guide/markdown#github-flavored-alerts), with dark mode support via the `.dark` class. See the [source code](https://github.com/lin-stephanie/rehype-callouts/tree/main/src/themes) for details.

If your site uses media-query-based dark mode, you can use [v2.1.0](https://github.com/lin-stephanie/rehype-callouts/releases/tag/2.1.0) or copy the styles manually. Suggestions for supporting both modes are welcome.

#### GitHub

![github](https://raw.githubusercontent.com/lin-stephanie/assets/refs/heads/main/rehype-callouts/github.png)

#### Obsidian

![obsidian](https://raw.githubusercontent.com/lin-stephanie/assets/refs/heads/main/rehype-callouts/obsidian.png)

#### VitePress

![vitepress](https://raw.githubusercontent.com/lin-stephanie/assets/refs/heads/main/rehype-callouts/vitepress.png)

## Examples

### Example: override default class names

The `props` option allows overriding the default class names generated by the plugin. The example from before can be changed like so:

```diff
import rehypeCallouts from 'rehype-callouts'
...

const file = unified()
  .use(remarkParse)
  .use(remarkRehype)
- .use(rehypeCallouts)
+ .use(rehypeCallouts, {
+   props: {
+     titleProps: { class: 'custom-class1' },
+     contentProps: { className: ['custom-class2', 'custom-class3'] },
+   },
+ })
  .use(rehypeStringify)
  .processSync(readSync('example.md'))

console.log(String(file))
```

…that would output:

```diff
<div class="callout" data-callout="note" data-collapsible="false">
- <div class="callout-title">
+ <div class="custom-class1">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <em>non-collapsible</em> callout
    </div>
  </div>
- <div class="callout-content">
+ <div class="custom-class2 custom-class3">
    <p>Some content is displayed directly!</p>
  </div>
</div>

<details class="callout" data-callout="warning" data-collapsible="true">
- <summary class="callout-title">
+ <summary class="custom-class1">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <strong>collapsible</strong> callout
    </div>
    <div class="callout-fold-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
  </summary>
- <div class="callout-content">
+ <div class="custom-class2 custom-class3">
    <p>Some content shown after opening!</p>
  </div>
</details>
```

### Example: custom attributes for callout elements

The `props` option allows adding custom attributes to elements in generated callouts. The example from before can be changed to add the [`dir: auto`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/dir) attribute to the outer container of both collapsible and non-collapsible callouts, and to set a custom color for `'note'` callouts, like so:

```diff
import rehypeCallouts from 'rehype-callouts'
...

const file = unified()
  .use(remarkParse)
  .use(remarkRehype)
- .use(rehypeCallouts)
+ .use(rehypeCallouts, {
+   props: {
+     containerProps(_, type) {
+       const newProps: Record<string, string> = {
+         dir: 'auto',
+       }
+       if (type === 'note') {
+         newProps.style = '--rc-color-light:#fc7777; --rc-color-dark:#fa9292;'
+       }
+       return newProps
+     },
+   },
+ })
  .use(rehypeStringify)
  .processSync(readSync('example.md'))

console.log(String(file))
```

…that would output:

```diff
<div
+ dir="auto"
+ style="--rc-color-light:#fc7777; --rc-color-dark:#fa9292;"
  class="callout"
  data-callout="note"
  data-collapsible="false"
>
  <div class="callout-title">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <em>non-collapsible</em> callout
    </div>
  </div>
  <div class="callout-content">
    <p>Some content is displayed directly!</p>
  </div>
</div>

<details
+ dir="auto"
  class="callout"
  data-callout="warning"
  data-collapsible="true"
>
  <summary class="callout-title">
    <div class="callout-title-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
    <div class="callout-title-text">
      This is a <strong>collapsible</strong> callout
    </div>
    <div class="callout-fold-icon" aria-hidden="true">
      <!-- svg icon-->
    </div>
  </summary>
  <div class="callout-content">
    <p>Some content shown after opening!</p>
  </div>
</details>
```

**Note:** In Svelte, using `dir="auto"` may trigger a compiler error. See [#15126](https://github.com/sveltejs/svelte/issues/15126) for details.

## Types

This package is fully typed with [TypeScript](https://www.typescriptlang.org/). It exports the additional types `UserOptions`, `CalloutConfig`, `TagsConfig`, `PropsConfig` and `CreateProperties`. See [jsDocs.io](https://www.jsdocs.io/package/rehype-callouts) for type details.

## Credits

- [staticnoise/rehype-obsidian-callout](https://gitlab.com/staticnoise/rehype-obsidian-callout) - basic functionality.
- [Octions](https://primer.style/foundations/icons/) - default icons for GitHub callouts.
- [Lucide](https://lucide.dev/) - default icons for Obsidian, VitePress callouts.

## Contribution

If you see any errors or room for improvement on this plugin, feel free to open an [issues](https://github.com/lin-stephanie/rehype-callouts/issues) or [pull request](https://github.com/lin-stephanie/rehype-callouts/pulls) . Thank you in advance for contributing!

## License

[MIT](https://github.com/lin-stephanie/rehype-callouts/blob/main/LICENSE) © 2024-PRESENT [Stephanie Lin](https://github.com/lin-stephanie)

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