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rehype-code-meta

This package is a unified (rehype) plugin to copy code.data.meta to code.properties.metastring.

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, and copies code.data.meta to code.properties.metastring.

When should I use this?

rehype-code-meta is useful if you use rehype-raw (hast-util-raw) since it destroys code.data.meta. Use rehype-code-meta to copy code.data.meta to code.properties.metastring to preserve tha data before rehype-raw (hast-util-raw).

Some rehype plugins utilize code.data.meta. Since rehype-raw destroys it, that rehype plugins also utilize code.properties.metastring in case rehype-raw is in the plugin chain.

Don't forget to remove code.properties.metastring in the end. The rehype plugins that utilize code.properties.metastring already remove it in most cases, hence you don't need to do anything.

Installation

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

npm install rehype-code-meta

or

yarn add rehype-code-meta

Usage

Say we have the following markdown file, example.md, and you want to add line numbering to the code via rehype-highlight-code-lines.

```javascript showLineNumbers
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 rehypeCodeMeta from "rehype-code-meta";
import rehypeRaw from "rehype-raw";
import rehypeHighlightCodeLines from "rehype-highlight-code-lines";
import rehypeStringify from "rehype-stringify";

main();

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

  console.log(String(file));
}

Now, running node example.js you see that the code lines are numbered thanks to rehype-code-meta. Otherwise, without rehype-code-meta, rehype-highlight-code-lines can't find the information showLineNumbers in the code.data.meta due to rehype-raw.

Options

There is no any option. It is opinionated.

Syntax tree

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

Types

This package is fully typed with TypeScript. The plugin doesn't export any type.

Compatibility

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

Security

Use of rehype-code-meta 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
• rehype-highlight-code-lines – Rehype plugin to add line numbers to code blocks and allow highlighting of desired code lines
• rehype-code-meta – Rehype plugin to copy code.data.meta to code.properties.metastring
• rehype-image-toolkit – Rehype plugin to enhance Markdown image syntax ![]() and Markdown/MDX media elements (<img>, <audio>, <video>) by auto-linking bracketed or parenthesized image URLs, wrapping them in <figure> with optional captions, unwrapping images/videos/audio from paragraph, parsing directives in title for styling and adding attributes, and dynamically converting images into <video> or <audio> elements based on file extension.

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.
• recma-mdx-change-imports – Recma plugin to convert import declarations for assets and media with relative links into variable declarations with string URLs, enabling direct asset URL resolution in compiled MDX.
• recma-mdx-import-media – Recma plugin to turn media relative paths into import declarations for both markdown and html syntax in MDX.
• recma-mdx-import-react – Recma plugin to ensure getting React instance from the arguments and to make the runtime props {React, jsx, jsxs, jsxDev, Fragment} is available in the dynamically imported components in the compiled source of MDX.
• recma-mdx-html-override – Recma plugin to allow selected raw HTML elements to be overridden via MDX components.
• recma-mdx-interpolate – Recma plugin to enable interpolation of identifiers wrapped in curly braces within the alt, src, href, and title attributes of markdown link and image syntax in MDX.

License

MIT License © ipikuka