komeiji

Generate a satori-friendly VDOM from a string of HTML.

Modern, Bun-ready successor of satori-html — drop-in API compatible, with the known upstream bugs fixed.

Why a rewrite

satori-html has not published a release since 2022-12 and crashes on every input under Bun 1.x (the bundled parsel selector engine cannot handle the :where([style]) rule the CSS inliner always injects). This library keeps the same API and output contract while:

	satori-html	komeiji
Bun / Node / Edge	crashes under Bun	works everywhere (tested on Bun 1.3 + Node 24)
HTML entities	& renders literally	decoded (HTML spec)
CSS custom props	--x corrupted to -X	preserved
Uppercase tags	DIV misses satori preset styles	lowercased (HTML spec)
Malformed style=""	tolerant	tolerant ({}), never throws
url(a;b.png) in styles	works	works
Types	any-heavy	strict, no any

Install

bun add komeiji        # or npm/pnpm

Usage

import satori from "satori";
import { html } from "komeiji";

const markup = html`<div style="color: black;">hello, world</div>`;
const svg = await satori(markup, {
  width: 600,
  height: 400,
  fonts: [],
});

The html utility can be used as a tagged template literal or as a plain function.

html`<div style="color: ${color};">hello</div>`;
html('<div style="color: black;">hello</div>');

<style> elements are parsed and inlined onto matching elements (class, id, tag and attribute selectors, comma lists, combinators; cascade ordered by specificity then source order; the inline style attribute always wins). At-rules such as @media are ignored, matching upstream behavior.

Elements whose class looks like Tailwind utilities get the class copied into the special tw prop, which satori consumes natively.

Example

A runnable OG-image example lives in examples/og-image.ts. It renders an 800x400 card from HTML (inline styles + a <style> block + Tailwind classes + interpolations) and writes examples/output.svg:

bun run example

<div style="display: flex; padding: 48px">
  <style>.brand { color: #6366f1; }</style>
  <h2 style="font-size: 40px">${title}</h2>
  <span class="brand">Start your free trial today.</span>
</div>

Deviations from satori-html

All render-equivalent through satori or strict improvements, and each is locked by a test:

• HTML entities are decoded in text and attribute values.
• children arrays never contain holes (comments and whitespace-only text are simply skipped; satori drops them anyway).
• Tag and attribute names are lowercased.
• CSS custom properties are preserved; vendor prefixes follow the React convention (-webkit-transform → WebkitTransform, -ms-flex → msFlex).
• Property names are case-insensitive (COLOR: works).
• Interpolations use the cooked template strings (Bun 1.3 mis-escapes astral characters in strings.raw).

Development

bun install
bun test        # unit + golden-render tests
bun run build   # tsc -> dist

The golden SVG snapshots in test/snapshots/ were captured once from satori-html@0.3.2 (via Node, where that package works) and are committed, so render parity with the reference is checked byte-for-byte on every test run without depending on it.

License

MIT