rehype-pre-language

This package is a unified (rehype) plugin to add language information of <code> element into <pre> element as a property.

unified is a project that transforms content with abstract syntax trees (ASTs) using the new parser micromark. remark adds support for markdown to unified. mdast is the Markdown Abstract Syntax Tree (AST) which is a specification for representing markdown in a syntax tree. "rehype" is a tool that transforms HTML with plugins. "hast" stands for HTML Abstract Syntax Tree (HAST) that rehype uses.

This plugin finds the <code> elements in hast, takes the language information and adds the language into <pre> element as "className" property by default or as a property provided in options.

When should I use this?

This plugin rehype-pre-language is useful if there is no language information in <pre> element but <code> element like <pre><code className="language-typescript"></pre>, and you need <pre> element to have language information.

Installation

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

npm install rehype-pre-language

or

yarn add rehype-pre-language

Usage

Say we have the following markdown file, example.md:

```javascript
const me = "ipikuka";
```

And our module, example.js, looks as follows:

import { read } from "to-vfile";
import remark from "remark";
import gfm from "remark-gfm";
import remarkRehype from "remark-rehype";
import rehypeStringify from "rehype-stringify";
import rehypePreLanguage from "rehype-pre-language";

main();

async function main() {
  const file = await remark()
    .use(gfm)
    .use(remarkRehype)
    .use(rehypePreLanguage)
    .use(rehypeStringify)
    .process(await read("example.md"));

  console.log(String(file));
}

Now, running node example.js you see that the <pre> element has a "class" with language information:

<pre class="javascript">
  <code class="language-javascript">const me = "ipikuka";</code>
</pre>

Without rehype-pre-language, the <pre> element wouldn't have a language information:

<pre>
  <code class="language-javascript">const me = "ipikuka";</code>
</pre>

Options

There is one string option which is a property of <pre> element in which the language information is going to be passed.

type PreLanguageOption = string; // the default is "className"

use(rehypePreLanguage, PreLanguageOption);

Examples:

// adds the language information into "className" of <pre> element as default
use(rehypePreLanguage);

// adds the language information into "className" of <pre> element
use(rehypePreLanguage, "className");

// adds the language information into "data-language" property of <pre> element
use(rehypePreLanguage, "data-language"); 

Syntax tree

This plugin modifies the hast (HTML abstract syntax tree).

Types

This package is fully typed with TypeScript.

The plugin exports the type PreLanguageOption.

Compatibility

This plugin works with rehype-parse version 1+, rehype-stringify version 1+, rehype version 1+, and unified version 4+.

Security

Use of rehype-pre-language involves rehype (hast), but doesn't lead to cross-site scripting (XSS) attacks.

My Plugins

I like to contribute the Unified / Remark / MDX ecosystem, so I recommend you to have a look my plugins.

My Remark Plugins

• remark-flexible-code-titles – Remark plugin to add titles or/and containers for the code blocks with customizable properties
• remark-flexible-containers – Remark plugin to add custom containers with customizable properties in markdown
• remark-ins – Remark plugin to add ins element in markdown
• remark-flexible-paragraphs – Remark plugin to add custom paragraphs with customizable properties in markdown
• remark-flexible-markers – Remark plugin to add custom mark element with customizable properties in markdown
• remark-flexible-toc – Remark plugin to expose the table of contents via vfile.data or via an option reference
• remark-mdx-remove-esm – Remark plugin to remove import and/or export statements (mdxjsEsm)

My Rehype Plugins

• rehype-pre-language – Rehype plugin to add language information as a property to pre element

My Recma Plugins

• recma-mdx-escape-missing-components – Recma plugin to set the default value () => null for the Components in MDX in case of missing or not provided so as not to throw an error
• recma-mdx-change-props – Recma plugin to change the props parameter into the _props in the function _createMdxContent(props) {/* */} in the compiled source in order to be able to use {props.foo} like expressions. It is useful for the next-mdx-remote or next-mdx-remote-client users in nextjs applications.

License

MIT License © ipikuka

Keywords

🟩 unified 🟩 rehype 🟩 rehype plugin 🟩 hast 🟩 markdown