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.mdx proposal

February 9, 2018 at 5:43pm
For a while now at ZEIT we've been using markdown-in-js as a pre-processor with Babel, so that we can write static documents more practically.
In practice, our pages end up looking something like this:
import * as components from './components/text'
import Video from ./components/video'
export markdown(components)`
# hello there
\`\`\`
My code snippet ${<Image />}
\`\`\`
`
In addition to letting us quickly write markdown, it has some really powerful benefits:
  • It's still JS, which means we can do imports, define helpers, assert that it's valid via a linter, etc.
  • We can embed JSX components inside Markdown. This is a must for us, because we like writing blog posts (https://zeit.co/blog) that have diverse content inside.
However, in my opinion, a lot of the benefits of "writing markdown" are lost. For example, as you see above, escaping code blocks becomes cumbersome.
As a result, I've been playing with an idea in my mind for a potential custom webpack loader and a new format called mdx, which brings the "best of both worlds" of JSX and Markdown.
Imagine my-blog-post.mdx:
import Video from '../components/video'
# My blog post
```
my code!
```
And here's a video:
<Video width={300} src="video.mp4" />
This looks great IMO, however, some important problems remain:
  • How do we lint? It should be impossible to include <Vid> because it's not imported, but <Video> should work. Can we extend eslint to understand .mdx ?
  • How do we defined the default set of components? One option would be to pass them to the webpack loader configuration
  • How do we override one component? Let's say we want to use a custom paragraph renderer. An idea here would be to standarize on a series of names, so that you can just do import P from '../components/paragraph'
  • How do we prettify it? Another issue we have with our markdown pages is that the markdown inside ends up looking really ugly, unless you painstakingly format it by hand. Can we extend prettier to understand .mdx?
If someone in the community wants to start playing around with a prototype, please share!
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February 9, 2018 at 6:50pm
What's nice about targeting `.jsx` code blocks is that editors/GitHub will syntax highlight, and a linter could quickly discern what is markdown and what is JSX. Though it's also not quite as expressive as inlined JSX in the document.
I would love to see this somewhat standardized in the community as .mdx. I've had to do it multiple times for different design systems' documentation, etc.
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3
Yeah, this is definitely a problem that most teams run into. Having a standardized specification with surrounding community built tooling will help us arrive at the best solution.
Of course and have already built something, why am I not surprised? 😉 Going to dig into that for the styled-components website, /cc
like-fill
1
I think the proper extension of markdown to allow custom React components to be embedded warrants the special syntax. Reasons for this are:
* We need both *block* level and *inline* level markup constructs for custom components. This is mainly due to how markdown markup is structured — I think you'd need this distinction to allow markdown and React components to be interleaved (e.g. pass some markdown to a React component as `children`).
* JSX (XML-like syntax) is too heavyweight to be embedded into markdown. I figured out you'd want to use such custom components often (there are a lot of use cases for them and not just for some ad-hoc uses).
I'v created a PoC quiet a while ago — https://andreypopp.github.io/reactdown (**warning:** it's not maintained) which exercises the points above by introducing a special syntax for block level and inline level constructs.
Reactdown isn't ready and is super alpha and outdated software, be warned. But I believe the idea is sound. :-)
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1
I've built something similar in the past and also overrode code blocks to allow them to execute. I liked the proposed style but the code blocks got highlighting for free. And allowed for running arbitrary js.
goes without saying that we’d need to make it agnostic of render target, but imagine how great this would be for writing transactional emails
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7
I'm not sure you guys aware of this: https://github.com/jamesknelson/mdxc
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1
It's awesome. I'm refactoring my blog to use it
mdxc is used in https://reactarmory.com/ for making interactive articles
It's definitely still an experiment, but we are consuming it as a library for some of our other experiments : )
It's really cool to see all these awesome projects in this area. Definitely shows that there's a need and is onto something with a formalized proposal. I'd personally love to see (and happy to help work on) some type of specification with standardized tools to blend markdown and JSX into a .mdx format.
This is a great idea! People have been wanting to do this for a while for Gatsby and just last week a contributor merged a PR adding support for this using rehype:
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1
Could you adjust the syntax like this to make it compatible with other frameworks/languages in the future?
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1
I prefer the original proposal. It's tempting to want to use fenced code blocks, but they add viewing and editing overhead beyond what markdown already has, with its inline HTML support. I think the popularity of next and styled-components despite needing editor plugins (also jsx in the early days) shows that iterating on the language is feasible. My only suggestion is adding a jsx tag for import so it's `<import Video="../components/video" />` or something.
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1
Wow, https://github.com/jamesknelson/mdxc is quite similar to this proposal! Even the import syntax is the same.
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2
I love that is the preview image for the zeit blog 😂
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February 10, 2018 at 12:16pm
Mdxc looks awesome!

February 12, 2018 at 9:11pm
Spent some time this weekend messing around with this mdx proposal and implementing it in c8r/markdown. So it's really a reimplementation of mdxc (project is so awesome) using remark.
This got me thinking that to really solve this problem and add support for linters, syntax highlighters, and code formatters like prettier we likely need a full-fledged abstract syntax tree. Also, parsing gets quite tricky with complex JSX containing maps, template strings and other JavaScript features. To me only partial JSX support, when inlined into markdown files would be confusing. Thus a full blown parser and AST could be quite useful.
I whipped up a quick MDXAST definition based on MDAST and HAST (copy pasta with a couple new node types): https://github.com/c8r/markdown/blob/master/MDXAST_SPECIFICATION.md
And tried to formally define .mdx since it kinda goes along with the notion of MDXAST:
Definitely interested about whether you fine folks have any other thoughts on this <3.
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5
My thoughts are: 🤯😍
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6

February 13, 2018 at 9:32am
I'd like to ask regarding what exactly are the requirements in using Javascript + Integrating Markdown ? Regarding creating content, what about going the other way ? E.g. using Markdown, typing code and with markdown parsers you can handle javascript code snippets ?
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1
🔥🔥🔥🔥🔥
that looks incredible!
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