# rehype-slug

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[**rehype**][rehype] plugin to add `id`s to headings.

## Install

[npm][]:

```sh
npm install rehype-slug
```

## Use

Say we have the following file, `fragment.html`:

```html
<h1>Lorem ipsum 😪</h1>
<h2>dolor—sit—amet</h2>
<h3>consectetur &amp; adipisicing</h3>
<h4>elit</h4>
<h5>elit</h5>
```

And our script, `example.js`, looks as follows:

```js
var fs = require('fs')
var rehype = require('rehype')
var slug = require('rehype-slug')

rehype()
  .data('settings', {fragment: true})
  .use(slug)
  .process(fs.readFileSync('fragment.html'), function(err, file) {
    if (err) throw err
    console.log(String(file))
  })
```

Now, running `node example` yields:

```html
<h1 id="lorem-ipsum-">Lorem ipsum 😪</h1>
<h2 id="dolorsitamet">dolor—sit—amet</h2>
<h3 id="consectetur--adipisicing">consectetur &#x26; adipisicing</h3>
<h4 id="elit">elit</h4>
<h5 id="elit-1">elit</h5>
```

## API

### `rehype().use(slug)`

Add `id` properties to h1-h6 headings that don’t already have one.

Uses [**github-slugger**][ghslug] to create GitHub style `id`s.

## Security

Use of `rehype-slug` can open you up to a [cross-site scripting (XSS)][xss]
attack as it sets `id` attributes on headings.
In a browser, elements are retrievable by `id` with JavaScript and CSS.
If a user injects a heading that slugs to an `id` you are already using,
the user content may impersonate the website.

Always be wary with user input and use [`rehype-sanitize`][sanitize].

## Related

*   [`remark-slug`](https://github.com/wooorm/remark-slug)
    — Add slugs to headings in markdown

## Contribute

See [`contributing.md`][contributing] in [`rehypejs/.github`][health] for ways
to get started.
See [`support.md`][support] for ways to get help.

This project has a [code of conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

## License

[MIT][license] © [Titus Wormer][author]

<!-- Definitions -->

[build-badge]: https://github.com/rehypejs/rehype-slug/workflows/main/badge.svg

[build]: https://github.com/rehypejs/rehype-slug/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/rehypejs/rehype-slug.svg

[coverage]: https://codecov.io/github/rehypejs/rehype-slug

[downloads-badge]: https://img.shields.io/npm/dm/rehype-slug.svg

[downloads]: https://www.npmjs.com/package/rehype-slug

[size-badge]: https://img.shields.io/bundlephobia/minzip/rehype-slug.svg

[size]: https://bundlephobia.com/result?p=rehype-slug

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[collective]: https://opencollective.com/unified

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[chat]: https://github.com/rehypejs/rehype/discussions

[npm]: https://docs.npmjs.com/cli/install

[health]: https://github.com/rehypejs/.github

[contributing]: https://github.com/rehypejs/.github/blob/HEAD/contributing.md

[support]: https://github.com/rehypejs/.github/blob/HEAD/support.md

[coc]: https://github.com/rehypejs/.github/blob/HEAD/code-of-conduct.md

[license]: license

[author]: https://wooorm.com

[rehype]: https://github.com/rehypejs/rehype

[ghslug]: https://github.com/Flet/github-slugger

[xss]: https://en.wikipedia.org/wiki/Cross-site_scripting

[sanitize]: https://github.com/rehypejs/rehype-sanitize