Modules ​

Short table of every source module, what it exports, and who imports it. Use this to figure out where to open the editor.

src/index.ts — CLI entry point ​

The binary's main(). Parses argv, prints the usage banner, and dispatches to one of serve, render, examples, llm, help, or version. No business logic — just argv → function call.

Exports: none (script entry). Imports: server.ts, cli.ts, version.ts, llm-docs/index.ts.

src/server.ts — HTTP server ​

startServer() spins up Bun.serve() on the configured host + port, routes requests to /render, /cache/:hash, /health, /examples, or 404. Handles auth with checkAuth().

Exports: startServer(config), ServerConfig interface. Imports: renderer.ts, cache.ts, examples.ts, version.ts, template.ts (type only).

src/cli.ts — CLI render + examples ​

• cliRender() reads JSON from stdin or a file, calls renderChart(), writes the image to stdout or a file, and echoes Chart.js messages to stderr.
• cliExamples() iterates EXAMPLES, calls renderChart() for each, writes NN-<slug>.{png,jpg} + NN-<slug>.json to --outdir.

Exports: cliRender, cliExamples, and their arg interfaces. Imports: renderer.ts, examples.ts, template.ts (type only).

src/renderer.ts — Chromium pipeline ​

The rendering core. Manages:

• Chromium discovery & auto-install — findChromiumExecutable(), downloadChromeForTesting(), ensureChromiumInstalled().
• Browser lifecycle — ensureBrowser(), launchBrowser(), closeBrowser(). Single module-level browser ref; launches lazily, auto-clears on disconnected.
• Page lifecycle — schedulePageCleanup() arms a setTimeout that force-closes the tab after PAGE_TIMEOUT_SECONDS.
• Render entry — renderChart() is the single export the rest of the codebase calls. It handles hash compute, cache get/set, semaphore acquire/release, HTML build, page.goto(data:…), console capture, screenshot.
• Stats — rendererStats() for /health.

Exports: renderChart, closeBrowser, rendererStats, ConsoleMessage, RenderResult. Imports: puppeteer-core, template.ts, semaphore.ts, cache.ts.

src/template.ts — Browser-side HTML ​

Static HTML string containing every CDN <script> for Chart.js + 12 plugins, and an IIFE that:

• registers non-auto-registering plugins (datalabels, chartjs-chart-geo);
• forces animations OFF;
• wraps console.warn / console.error into window.__chartMessages;
• instantiates Chart inside try/catch;
• sets window.__chartRendered = true when done.

Edit this file if you add/remove/upgrade a plugin. See Adding a Chart.js plugin.

Exports: buildHtml(options), RenderOptions interface, LIBS const. Imports: none.

src/cache.ts — In-memory cache ​

Map<string, CacheEntry> with LRU-ish eviction (oldest key evicted when size >= MAX_ENTRIES) and TTL (lazy expiry on getCache). computeHash() hashes {chart, width, height, devicePixelRatio, backgroundColor, format, quality} via SHA-256 and takes the first 16 hex chars.

Exports: computeHash, getCache, setCache, cacheStats. Imports: crypto (Node built-in), template.ts (type only).

src/semaphore.ts — Concurrency control ​

30-line async semaphore. acquire() returns immediately if under capacity, otherwise pushes a resolver into a FIFO queue. release() pops the head of the queue and resolves.

Exports: Semaphore class. Imports: none.

src/examples.ts — Built-in examples ​

EXAMPLES is an array of { title, config, width?, height? } used by:

• The CLI's examples subcommand (writes PNG + JSON files)
• The HTTP /examples gallery (embeds <img src="/render?chart=…"> tags)

Add new examples here; they show up in both the CLI output directory and the gallery page automatically.

Exports: EXAMPLES, buildExamplesHtml(). Imports: none.

src/version.ts — Version constant ​

Single-line module re-exporting VERSION from package.json (via Bun's await import(..., { type: 'json' }), so compile-time inlined by bun build).

Exports: VERSION. Imports: package.json.

src/llm-docs/ — LLM reference bundle ​

One TS file per Chart.js module. Each file exports doc: string — a multi-line Markdown snippet. llm-docs/index.ts aggregates them into getLlmDocs() which chartjs2img llm prints.

See Adding LLM docs.

The files ​

Dependency graph (roughly) ​

No cyclic deps. Nothing imports server.ts or cli.ts except index.ts — keeping entry points thin.