remark-pdfmake

日本語

A unified-based pipeline that converts Markdown into pdfmake's TDocumentDefinitions (docDefinition) and renders it straight to PDF bytes. No headless browser (Puppeteer, etc.) required — PDFs are generated in plain Node.js.

Why

Generating PDFs through a headless browser carries the cost of launching a Chrome process, port exhaustion, and heavy resource usage under concurrency. remark-pdfmake avoids the Markdown → HTML → CSS rendering path entirely, converting Markdown's structure directly into pdfmake's layout elements (text/stack/table/ul/ol/ canvas/image), sidestepping these problems.

Pipeline

markdown --(remark-parse, remark-gfm)--> mdast
        --(remark-rehype + rehype-raw)--> hast
        --(rehypeToDdast)--> ddast
        --(styleTransform + theme)--> ddast (styled)
        --(pdfmakeCompiler)--> docDefinition
        --(pdfmake)--> PDF

See ARCHITECTURE.md for the responsibilities and constraints of each stage. The ddast (Document Definition AST — a unist-compliant syntax tree whose vocabulary is pdfmake's own elements) spec itself lives in src/ddast/README.md.

Supported Markdown syntax: GFM (tables, strikethrough, task lists, etc.), raw HTML embedded in the body (<br>, <small>, etc.), and two pdfmake-only markers — <!-- width="..." --> (a table column's preferred width) and <!-- pdf-page-break --> (a forced page break) — which are HTML comments, so they render invisibly in any other Markdown viewer.

Install

npm install remark-pdfmake

ESM-only package (no require() support, since its unified/remark/rehype dependencies are all ESM-only). Requires Node.js 22 or later.

Usage

import { markdownToDocDefinition, renderToFile, loadFonts, DEFAULT_THEME } from "remark-pdfmake";

// Which fonts to use, under which name, and where to fetch them from is entirely up
// to the caller — remark-pdfmake has no opinion on this (see sample/generate.ts for a
// complete example with CJK support and a monospace code font).
const fonts = await loadFonts(fontCacheDir, {
  MyFont: { normal: { filename: "MyFont-Regular.ttf", url: "https://example.com/MyFont-Regular.ttf" } },
});

const dd = markdownToDocDefinition(markdown, {
  defaultStyle: { font: "MyFont", fontSize: 10 },
  theme: DEFAULT_THEME,
});
dd.pageSize = DEFAULT_THEME.page.size;
dd.pageMargins = DEFAULT_THEME.page.margins;

// renderToFile()/renderToBuffer() require this argument (no default) — pdfmake reads
// local files and fetches remote URLs on your behalf, and it's your call which of those
// to allow. Pass {} if you don't want any restriction. A rejected path/URL makes pdfmake
// throw (fail-closed) rather than silently skip it, so wrap this call in try/catch when
// processing untrusted markdown.
await renderToFile(dd, fonts, "output.pdf", {
  localAccessPolicy: (path) => path.startsWith(fontCacheDir),
  urlAccessPolicy: () => false,
});

It also works directly as a unified Processor (extendable with .use()):

import { createProcessor } from "remark-pdfmake";

const file = createProcessor({ theme: DEFAULT_THEME }).processSync(markdown);
const dd = file.result; // TDocumentDefinitions

...and as a remark plugin (default export), so it can be plugged into an existing remark pipeline:

import { remark } from "remark";
import remarkPdfmake from "remark-pdfmake";

const file = remark().use(remarkPdfmake, { theme: DEFAULT_THEME }).processSync(markdown);
const dd = file.result; // TDocumentDefinitions

For a smaller working example, see sample/ (running sample/generate.ts with npx tsx generates sample/report.pdf from sample/report.md).

Fonts

remark-pdfmake has no opinion on which fonts to use — the caller decides which fonts, under which names, and from where, and hands that as a FontSourceMap to loadFonts() (see src/render/fonts/fonts.ts), which fetches/caches them at runtime (font files are not bundled in the repository) and resolves them into the TFontDictionary renderToFile()/renderToBuffer() expect. sample/generate.ts is a complete example that chooses Noto Sans CJK JP (Japanese) and Roboto Mono (monospace code elements), both distributed under the SIL Open Font License — see sample/licenses/README.md for the licensing rationale for that specific choice.

Pre-publish verification

pnpm test/pnpm run typecheck only verify against this repository's own tsconfig.json (moduleResolution: "Bundler"). Whether the published type declarations (dist/**/*.d.mts) resolve on their own under a consumer's moduleResolution: "nodenext" environment is verified separately with pnpm run verify:nodenext (it installs the packed tarball into a clean project and runs tsc --noEmit; this is excluded from the regular test run since it requires network access).

License

MIT