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Debugging Jet templates

When a layout condition doesn't fire or a frontmatter field comes out blank, guessing is slow. Two built-in functions let you see exactly what the template engine sees: debug() and note.M().Debug().

These are for use inside custom Jet layouts in _layouts/. If you use the default template without custom HTML, you don't need this page.

note.M().Debug() — dump all frontmatter

note.M() returns the note's metadata object. Calling .Debug() on it prints all frontmatter keys as a JSON string, inline in the rendered page:

{{ note.M().Debug() }}

Output:

{"extra_content":["channels","prices"],"layout":"my-page","title":"My Page"}

This answers the question "what frontmatter does the template actually receive?" — useful when a {{ if note.M().Has("featured") }} block never renders and you want to confirm the key is present.

debug() — inspect any expression

The global debug() function takes any expression and returns its Go type, current value, and full list of available methods:

{{ debug(note.M()) }}

Output (rendered as inline text):

*templateviews.Meta: &{raw:map[title:My Page extra_content:[a b]]}
      methods: [Debug Get GetBool GetInt GetString GetStrings Has Raw]

You can pass any expression — a string, a number, the result of a method call:

{{ debug(note.Title()) }}
{* → string: My Page *}

{{ debug(note.M().GetStrings("tags", nil)) }}
{* → []string: [go obsidian] *}

Always call methods with parentheses. debug(note.Title()) inspects the string "My Page". debug(note.Title) inspects the function reference itself — not what you want.

Before and after: why a condition fails

Suppose you have a layout that shows a "Featured" badge on certain notes:

{{ if note.M().Has("featured") }}
  <span class="badge">Featured</span>
{{ end }}

The badge never appears. You add a debug call to check what the template sees:

{{ note.M().Debug() }}
{{ if note.M().Has("featured") }}
  <span class="badge">Featured</span>
{{ end }}

The output shows:

{"layout":"article","title":"Top Post"}

The key featured is missing. Back in Obsidian, the note has Featured: true — capital F. Frontmatter keys are case-sensitive. Rename the property to featured: true, sync, and the badge appears.

Without debug(), you'd be checking sync status, cache, or template logic. With it, you see the real data in one render.

Workflow: debug without uploading

You don't have to sync a file to the vault every time you add a debug call. Use /_system/renderlayout to render any template against any note content from the terminal — see renderlayout for the full API.

Quick example — check what frontmatter a note exposes:

node scripts/trip2g-preview.mjs \
  --layout-src '{{ note.M().Debug() }}' \
  --layout-path '/_debug.html' \
  --note-path /my-post \
  --fetch

The --fetch flag prints the rendered HTML directly to stdout. No browser needed, no file sync.

Remove debug calls before publishing

debug() and .Debug() output raw Go internals directly into your HTML. Readers see this text on the page. Remove all debug calls before syncing a final version.

A safe pattern during development: put debug calls inside Jet comments so they render but are easy to find and delete:

{* DEBUG: {{ note.M().Debug() }} *}

Jet comments don't appear in the output — but that also means you won't see the result. Use a plain {{ }} block while debugging, switch to a {* *} comment when you're done checking, then delete the line entirely before publishing.

  • templates — how Jet layouts work, available variables, and template syntax
  • renderlayout — render a layout against any note without uploading files