JIM Specification

JIM (JavaScript in Markdown) is Markdown in which {{…}} holds a JavaScript expression. Rendering evaluates each expression and splices the result into the text. The output is Markdown.

For the practical guide, see Writing pages.

# Photos

{{ photos.map(p => `![${p.location}](${p.image})`).join("\n") }}

Evaluation

• {{…}} contains a single JavaScript expression. Statements need an IIFE.
• Expressions evaluate against an environment supplied by the host. JIM defines no globals.
• The result becomes text: a string is spliced as-is, null and undefined become nothing, an array becomes its elements' text concatenated, any other value becomes String(value).
• Everything outside {{…}} passes through untouched. \{{ produces a literal {{.
• An evaluation error fails the render with a message naming the failing expression.

File form

A JIM document may open with a frontmatter block fenced by --- lines. The block is JavaScript, run once per render against the host environment. Its top-level const, let and var declarations become additional bindings for the body's expressions; declarations may reference each other.

---
const photos = resources["travel-photos"].filter(p => p.country === "New Zealand")
const count = photos.length
---
# Photos ({{ count }})

{{ photos.map(p => `![${p.location}](${p.image})`).join("\n") }}