The author is lying. The source isn't actually a markdown document, the source is HTML (you can easily verify this by right-clicking and selecting "View Source")
It's actually quite easy to actually render markdown pages in a browser. Start with this:
document.write('<link rel="stylesheet" href="css/style.css">'));
document.addEventListener('DOMContentLoaded', (event) => {
var m = markdownIt({'html': true, 'linkify': true});
var t = document.querySelector('textarea');
var d = document.createElement('div');
d.setAttribute('id', 'content');
d.innerHTML = m.render(t.value);
t.replaceWith(d);
});
I think the author means that they wrote a markdown document, which then was transformed (by a CI/CD pipeline, for example) to the html you see when you inspect the source.
I like your "Serve markdown, transform through a client-side script" approach though, so upvoting nonetheless.
It's actually quite easy to actually render markdown pages in a browser. Start with this:
and "notes-all.js" contains something like this: followed by markdown-it source code