rehype-concat-css-style

rehype plugin to concatenate <style>s together.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • unified().use(rehypeConcatCssStyle)
• Example
• Syntax
• Syntax tree
• Types
• Compatibility
• Security
• Contribute
• License

What is this?

This package is a plugin that can improve performance by merging multiple CSS <style> elements together. This plugin can be dangerous if CSS is invalid. Additionally, this plugin does not handle scoped styles. Those are deprecated anyway.

When should I use this?

You can use this plugin when you are certain that your CSS is valid and you want to improve the size of HTML.

Install

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

npm install rehype-concat-css-style

In Deno with esm.sh:

import rehypeConcatCssStyle from 'https://esm.sh/rehype-concat-css-style@4'

In browsers with esm.sh:

<script type="module">
  import rehypeConcatCssStyle from 'https://esm.sh/rehype-concat-css-style@4?bundle'
</script>

Use

On the API:

import rehypeConcatCssStyle from 'rehype-concat-css-style'
import rehypeParse from 'rehype-parse'
import rehypeStringify from 'rehype-stringify'
import {read} from 'to-vfile'
import {unified} from 'unified'

const file = await unified()
  .use(rehypeParse)
  .use(rehypeConcatCssStyle)
  .use(rehypeStringify)
  .process(await read('index.html'))

console.log(String(file))

On the CLI:

rehype input.html --use rehype-concat-css-style --output output.html

On the CLI in a config file (here a package.json):

 …
 "rehype": {
   "plugins": [
     …
+    "rehype-concat-css-style",
     …
   ]
 }
 …

API

This package exports no identifiers. The default export is rehypeConcatCssStyle.

unified().use(rehypeConcatCssStyle)

Concatenate <style> elements together.

Returns

Transform (Transformer).

Example

In

<style>b{color:red}</style>
<style>i{color:blue}</style>

Out

<style>b{color:red}i{color:blue}</style>

Syntax

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

Syntax tree

The syntax tree used is hast.

Types

This package is fully typed with TypeScript.

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-concat-css-style@^4, 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.

Contribute

See contributing.md in rehypejs/.github for ways to get started. See support.md for ways to get help.

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

License

MIT © Titus Wormer