Rehype NPM | npm.io

rehype

unified processor to add support for parsing from HTML and serializing to HTML.

What is this?

This package is a unified processor with support for parsing HTML as input and serializing HTML as output by using unified with rehype-parse and rehype-stringify.

See the monorepo readme for info on what the rehype ecosystem is.

When should I use this?

You can use this package when you want to use unified, have HTML as input, and want HTML as output. This package is a shortcut for unified().use(rehypeParse).use(rehypeStringify). When the input isn’t HTML (meaning you don’t need rehype-parse) or the output is not HTML (you don’t need rehype-stringify), it’s recommended to use unified directly.

When you’re in a browser, trust your content, don’t need positional info on nodes or formatting options, and value a smaller bundle size, you can use rehype-dom instead.

When you want to inspect and format HTML files in a project on the command line, you can use rehype-cli.

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install rehype

In Deno with esm.sh:

import {rehype} from 'https://esm.sh/rehype@13'

In browsers with esm.sh:

<script type="module">
  import {rehype} from 'https://esm.sh/rehype@13?bundle'
</script>

Use

Say we have the following module example.js:

import {rehype} from 'rehype'
import rehypeFormat from 'rehype-format'

const file = await rehype().use(rehypeFormat).process(`<!doctype html>
        <html lang=en>
<head>
    <title>Hi!</title>
  </head>
  <body>
    <h1>Hello!</h1>

</body></html>`)

console.error(String(file))

…running that with node example.js yields:

<!doctype html>
<html lang="en">
  <head>
    <title>Hi!</title>
  </head>
  <body>
    <h1>Hello!</h1>
  </body>
</html>

API

This package exports the identifier rehype. There is no default export.

`rehype()`

Create a new unified processor that already uses rehype-parse and rehype-stringify.

You can add more plugins with use. See unified for more information.

Examples

Example: passing options to `rehype-parse`, `rehype-stringify`

When you use rehype-parse or rehype-stringify manually you can pass options directly to them with use. Because both plugins are already used in rehype, that’s not possible. To define options for them, you can instead pass options to data:

import {rehype} from 'rehype'
import {reporter} from 'vfile-reporter'

const file = await rehype()
  .data('settings', {
    emitParseErrors: true,
    fragment: true,
    preferUnquoted: true
  })
  .process('<div title="a" title="b"></div>')

console.error(reporter(file))
console.log(String(file))

…yields:

1:21-1:21 warning Unexpected duplicate attribute duplicate-attribute hast-util-from-html

⚠ 1 warning

<div title=a></div>

Syntax

HTML is parsed and serialized according to WHATWG HTML (the living standard), which is also followed by all browsers.

Syntax tree

The syntax tree format used in rehype is hast.

Types

This package is fully typed with TypeScript. It exports no additional types.

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, rehype@^13, compatible with Node.js 16.

Security

As rehype works on HTML, and improper use of HTML can open you up to a cross-site scripting (XSS) attack, use of rehype can also be unsafe. Use rehype-sanitize to make the tree safe.

Use of rehype plugins could also open you up to other attacks. Carefully assess each plugin and the risks involved in using them.

For info on how to submit a report, see our security policy.