Access frontmatter after compile with outputFormat: "function-body"

[openscript]

Dear mdx-js community

I wonder if I can access the frontmatter when I compile(page.default, { ...mdxOptions, outputFormat: "function-body" }); somehow without running?

I've read https://mdxjs.com/guides/frontmatter/ and loaded already remarkPlugins: [remarkFrontmatter, remarkMdxFrontmatter].

Thank you for your help

[wooorm]

Yes, you should be able to access it when running when you use both those two plugins. Do a console.log(await run(...)), it’ll print the component at a default field, and will have other fields with your frontmatter!

[wooorm]

Then you don’t need remarkFrontmatter, remarkMdxFrontmatter, as those do the other part: exposing frontmatter when running.

If you don’t run, then yo can use any old frontmatter thing. As remco points out: vfile-matter is one by us that we often use!

[remcohaszing]

remarkFrontmatter is still needed to add frontmatter syntax support to the MDX content.

[openscript]

Thank you for your help! I didn't know about vfile before. What a nice and clean format!

I've seen that compile already creates a vfile and all the work with splitting off the frontmatter is already done by then. Wouldn't it be very handy to make frontmatter available in vfile.data?

[wooorm]

That’s what vfile-matter indeed does!
compile indeed returns a vfile, with the compiled javascript as a result.
It also accepts a vfile, with the input markdown/mdx (with/without frontmatter).

You can put vfile-matter in a plugin, and pass that to compile. Then you get what you want too.
Or you can create a vfile first, call vfile-matter with that file, and pass that file to compile. That’s what I’d do.

[remcohaszing]

You can use vfile-matter to access frontmatter data without running the code.