I did it! The
gatsby-transform-remark bug I've been working on for a month yields to my assault!
Not because it's that difficult of a bug. Oh no. Because I was doing dumb things and jumping into a large project like Gatsby is hard.
Previous attempts failed first because I couldn't get my dev environment to work and then because I made a newbie mistake with
yarn.lock and got frustrated.
The bug was more of a feature, really. When Remark generates a table of contents out of your markdown headers, it uses relative links. Like this:
# Heading ## Subheading 1 ## Subheading 2 ### Subsubheading ## Subheading 3
That turns into an HTML list with
#subheading-1 (etc) links. Nesting at all.
- Heading (#heading) - Subheading 1 (#subheading-1) - Subheading 2 (#subheading-2) - Subsubheading (#subsubheading) - Subheading 3 (#subheading-3)
Imagine all of that is HTML with
<a> tags. Laying it out like this is easier to read.
This works great when you're only putting tables of contents on each individual page. Render a markdown document, put a TOC on top. Perfect.
But it stops working if you want to make a main table of contents for all your documents. All those relative links stop working.
Subheading is on an actual path now.
The fix was to prepend slugs to every URL that
mdast-util-toc generates. The best place to do that was deep inside
gatsby-transform-remark, in a file called
As far as I can tell, that file is the whole of the markdown transformer. It takes a markdown GraphQL node (flat text at this point) and extends it into something Gatsby can read to make a React-based HTML page.
Our fix went into the aptly named
This happens after all the processing that turns a markdown file into an abstract syntax tree (AST). Basic recursion:
- Get node.
- If node has
url, change it.
- If node has children, call
Looks simple now that it works, but it sure took a while. Large codebases are fun like that.
Now just gotta figure out how to get absolute absolute paths working. You know, when you're not deploying your site to
/ but to
/something/. Something to do with the
--prefix-paths flag when compiling.