Add rehype-mdx-toc to export toc to list of plugins

[boning-w]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything or linked relevant results below
• I made sure the docs are up to date
• I included tests (or that’s not needed)

Description of changes

Add a rehype plugin rehype-mdx-toc that allows users to export the table of contents (TOC) data as a named export from an MDX module.

Why another table of contents plugin?

Since MDX supports exporting data from MDX modules, it's much more convinent to export the TOC — so that users can use it whatever they like, just like with remark-mdx-frontmatter.

Simple usage:

import { compile, run } from "@mdx-js/mdx";
import rehypeMdxToc from "rehype-mdx-toc";
import * as runtime from "react/jsx-runtime";

const mdxContent = `
# Heading 1
## Heading 2
### Heading 3
`;

const compiled = await compile(mdxContent, {
  outputFormat: "function-body",
  rehypePlugins: [rehypeMdxToc],
});
const result = await run(compiled, { ...runtime });
const toc = result.toc;
console.log(toc);

With some bundlers — like @mdx-js/esbuild, @mdx-js/rollup, and @mdx-js/loader, we can easily import the TOC data at build time:

import MDXContent, { toc } from "./you-mdx-file.mdx";

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
mdx	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 5, 2025 3:19am

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (908ff45) to head (6a728d2).
Report is 91 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files           23        21    -2     
  Lines         2693      2650   -43     
  Branches         2         2           
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- Hits          2693      2650   -43     

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[wooorm]

Thank you, cool!

[boning-w]

Thank you all!