Tern

Documents with the full power of HTML, CSS and JavaScript. A note is one HTML file: its first line loads tern.js, and everything below it is written in Tern’s syntax and rendered in place when the file is opened.

# Linear maps {#maps}

:::theorem[Rank–nullity]{#thm-rn}
If $V$ is finite-dimensional then $\dim V = \dim \ker T + \dim \operatorname{im} T$.
:::

By @thm-rn, an injective map between spaces of equal dimension is surjective.

Documentation

The documentation is published at ozkrac.github.io/tern. Start with the guide. The pages are themselves Tern notes: the same files are index.html and docs/ in this repository, and they open locally in a browser too.

Getting tern.js

A note needs only tern.js

:::use
themes/nord.css
addons/katex.js
addons/code.js
:::

One add-on also fits on the tag, as data-use="addons/katex.js"; both forms work together.

From jsDelivr, which serves this repository’s tagged releases:

• To follow releases, use @0.6 (the newest 0.6.x) or @latest (the newest release).
• Not tern.min.js. jsDelivr minifies any file on request, so tern.min.js exists beside tern.js at every tag and renders a note in the browser; do not use it. The tools and the editors take a note only from a tag whose file is called tern.js. Where bytes matter, each GitHub Release carries a minified build under that name: https://github.com/OzkrAC/tern/releases/download/vX.Y.Z/tern.js, or copy it to your site.

Themes: themes/ holds colour themes after well-known palettes (Solarized, Gruvbox, Nord, Dracula, Catppuccin, Tokyo Night and more), each an add-on: themes/nord.css in :::use (or data-use), or the same path on jsDelivr. See themes.

Add-ons: addons/ holds add-ons that come with Tern: code.js colours code by its language, and mermaid.js draws mermaid fences as diagrams, both in the theme’s colours; katex.js and mathml.js typeset math; search.js gives a ::search box over a set of notes, indexed in the browser or from the index tern index writes; notes.js lists the notes of a folder from the same command’s catalogue. List them in :::use, one per line. See add-ons.

With npm, from this repository: npm install github:OzkrAC/tern#vX.Y.Z (a tag) puts the same tern.js, tern.css, the add-ons and the themes under node_modules/@ozkrac/tern/, with type declarations and the tern command (Under node). The package is not on the npm registry.

Using the CLI tool

npm install -g github:OzkrAC/tern#vX.Y.Z installs the tern command from a tag; npx github:OzkrAC/tern#vX.Y.Z … runs it without installing; in a checkout, node tern-cli.js …:

node tern-cli.js new notes/linear-maps.html     # write the first line
node tern-cli.js check notes/                    # diagnostics and broken links, with file lines
node tern-cli.js build notes/linear-maps.html -o out.html   # a static, pre-rendered page
node tern-cli.js mv notes/linear-maps.html notes/algebra/    # move it, rewriting the links to and from it
node tern-cli.js vendor vendor/                  # local copies of KaTeX, highlight.js, Mermaid and Temml, for ?base=
node tern-cli.js search "rank nullity" notes/              # the sections and blocks that use these words, with lines
node tern-cli.js index notes/                    # notes.json and search.json, what ::notes and ::search read
node tern-cli.js lsp                              # the language server, over stdio

Named blocks such as :::theorem get labels, counters and elements from a schema: an add-on listed in :::use (or data-use), or window.TERN = {schema: …} in a script before the tern.js line (Vocabulary and behaviour).

Editors

• Neovim: tern.nvim runs the language server and adds the commands (:TernCheck, :TernBuild, :TernSearch …), with the outline and a preview.
• Any editor with a language-server client: node tern-cli.js lsp speaks LSP over stdio: diagnostics as the browser reports them, completion, hover, definition, references, rename, symbols, folding, and link fixes when a file is moved. Setup, and the note-detection rule an editor needs, in Command line and editors.

Agent skills

skills/tern-notes teaches coding agents (GitHub Copilot, Claude Code, Codex, Cursor) to write, check and fix notes. Install it in a project with gh skill install OzkrAC/tern tern-notes, or copy it into the project’s .github/skills/ (skills/README.md).

Development

CONTRIBUTING.md says how a change is made and tested; SECURITY.md how to report a security problem.

npm run build       # src/ → tern.js and tern.css
npm test            # build check, corpus, samples, perf, fuzz, API, CLI, LSP, documentation
npm run smoke       # Chromium and Firefox (Playwright)

A release. npm run bump -- X.Y.Z (or patch, minor, major) sets the new version everywhere it is written: package.json, tern.version, the README’s jsDelivr tag and the docs’ examples. It rebuilds tern.js, starts the version’s section in CHANGELOG.md, and refuses a version that is already a tag. Write the changelog section, run npm test, commit, and once the commit is on main, run npm run tag: it refuses what the release workflow would (a branch other than main, a working tree with changes, a place that disagrees, a missing changelog section, a tag that exists), then creates vX.Y.Z. Push the tag (git push origin vX.Y.Z): the release workflow checks it against the version, runs every test, publishes the site, drafts the GitHub Release with the changelog section as its notes and three assets (a minified tern.js, built with a pinned terser and checked to be the same version; tern.css; tern-vX.Y.Z.zip holding tern.js, tern.css, tern.d.ts, the add-ons and the themes), Publish the draft. The package is not published to the npm registry; npm install github:OzkrAC/tern#vX.Y.Z installs the tag. npm test fails if any place disagrees with package.json, or if a file names the version where tools/version.js does not look, so a new mention cannot be missed at the next bump.

MIT licensed.

AI assistance

Tern is developed with the help of an AI coding assistant.