rehype-concat-css-style

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 12.20+, 14.14+, or 16.0+), install with npm:

npm install rehype-concat-css-style

In Deno with esm.sh:

import rehypeConcatCssStyle from 'https://esm.sh/rehype-concat-css-style@3'

In browsers with esm.sh:

<script type="module">
  import rehypeConcatCssStyle from 'https://esm.sh/rehype-concat-css-style@3?bundle'
</script>

Use

On the API:

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

main()

async function main() {
  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. There are no options.

Example

In

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

Out

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

Syntax

HTML is handled according to WHATWG HTML (the living standard), which is also followed by browsers such as Chrome and Firefox.

Syntax tree

The syntax tree format used is hast.

Types

This package is fully typed with TypeScript.

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

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