Template Syntax

hyogen.md extends Markdown with HTML-comment directives and Mustache-style expressions. Everything below is available in @b4moss/hyogen-md@0.14.0.

Two layers

Layer	Where	What you can write
Expressions	`{{ }}` / `{{{ }}}` in Markdown body; `${}` inside code fences	Expressions only — no statements
Logic blocks	`<!-- @hg … @endhg -->` or `<!--@@ … @@-->`	Declarations, includes, `if` / `each`, and more

Topics

Data and output

Front matter — YAML metadata and component props
Expressions — {{ }}, defaults, ternary, fence ${}
Methods — .toLocaleString, allowed property .length

Blocks and directives

Hyogen blocks — @hg / @endhg and @@ shorthand
Declarations — const, let, reassignment
Includes and components — include, component … as, extend + block
Control flow — if / else / each
TOC helper — toc / toc(N) table of contents

Safety

Paths and security — .doc_root, _ partials, XSS notes

Minimal example

---
title: Greeting
---

# {{ title }}

<!--
@hg
const name = "world"
@endhg
-->

Hello {{ name | "stranger" }}!

Rendered:

# Greeting

Hello world!

Try it in the Playground.