This is a Livecoding Recap – an almost-weekly post about interesting things discovered while livecoding. Usually shorter than 500 words. Often with pictures. Livecoding happens almost every Sunday at 2pm PDT on multiple channels. You should follow My Youtube channel to catch me live.

Ah, it’s good to be back. It’s been what, a month? Long time no see as the first person to say hi in the chatroom said.

We continued to work on GatsbyJS. That one feature I want to add: Make links in markdown tables of contents absolute.

Instead of #some-title the link should be /page-slug#some-title. That way users can put tables of contents on their index pages and link into documents directly.

The first difficulty was using VSCode. I wanted to give it a fairer shot at impressing me after all the configuration advice people gave me on Friday.

Also, this killer feature looks cool and I want it.

I’ll talk more about VSCode after I use it some more.

The other difficulty was that I have no idea what I’m doing. At first, I was editing the wrong file. My code kept vanishing every time compilation did its thing.

Turns out there’s a big difference between gatsby-transform-remark/extend-node-type.js and gatsby-transform-remark/src/extend-node-type.js.

Confusing for a newbie that those two files are so close together, but it makes sense. Gatsby uses something called Lerna to create a multirepo. Every folder inside the repository is its own package.

When I figured that out, I had the bright idea to update my local clone to latest master.

It did not go so well.

It went so not well, in fact, that we never got to the real work. I don’t know how many times I installed and reinstalled node_modules, but nothing worked.

This ate all the time I had, and we got nothing done.

I mean, sure, we explored how the markdown AST stuff works, where we need to add the slug (it’s deep inside children of children), and made a reasonable hypothesis that we can get the slug using markdownNode.fields.slug.

The hypothesis stems from this: We know that each Gatsby node has a fields.slug. Don’t know where it comes from, but docs assure us it’s there. Not sure markdownNode is that node, but what else could it be?

markdownNode is the node that we are extending, therefore it must be the same thing as a normal Gatsby node. It’s just called markdownNode here because we’re operating on markdown.

This is the function we’re tweaking by the way πŸ‘‡

    async function getTableOfContents(markdownNode) {
      const cachedToc = await cache.get(tableOfContentsCacheKey(markdownNode))
      if (cachedToc) {
        return cachedToc
      } else {
        const ast = await getAST(markdownNode)
        const tocAst = mdastToToc(ast)
        let toc
        if ( {
          toc = hastToHTML(toHAST(
        } else {
          toc = ``
        cache.set(tableOfContentsCacheKey(markdownNode), toc)
        return toc

That tocAst is where we inject our tweak. I think πŸ€”

Oh right! The newbie mistake fix πŸ‘‰ Matthew of Gatsby fame informed me that my yarn.lock was probably out of date. It was.

Learned something new? Want to become a better engineer? πŸ’Œ

Join 9,400+ people just like you already improving their skills.

Here's how it works πŸ‘‡

Leave your email and I'll send you an Interactive Modern JavaScript Cheatsheet πŸ“– right away. After that you'll get a thoughtfully written email every week aboutΒ React, JavaScript,Β  andΒ lessons learned in my 20 years of writing code for companies ranging from tiny startups to Fortune5 behemoths.

Man, I love your way of writing these newsletters. Often very relatable and funny perspectives about the mundane struggles of a dev. Lightens up my day. ~ Kostas

PS: You should also follow me on twitter πŸ‘‰ here.
It's where I go to shoot the shit about programming.