@mermanjs/node-wasm

Explicit Node-targeted WebAssembly rendering for Node.js 22+ and static-site build pipelines. This is a separate opt-in package; @mermanjs/node remains the native N-API package and never silently falls back to browser or Node WASM.

Quick start

npm install @mermanjs/node-wasm@alpha

import { createNodeEngine } from "@mermanjs/node-wasm";

const engine = await createNodeEngine();

try {
  const svg = await engine.renderSvg("flowchart TD\nA --> B");
  console.log(svg);
} finally {
  await engine.dispose();
}

The package embeds a Node-targeted wasm-bindgen artifact and does not depend on @mermanjs/web. It is intended for Node-only server-side rendering and static generation. The WASM transport is single-threaded, so an AbortSignal cannot interrupt an operation after it enters the candidate; operation deadlines remain available through timeoutMs.

renderSvg() and renderSvgSync() use the parity pipeline by default. This preserves the Mermaid-compatible SVG structure for trusted input and parity-sensitive consumers. For SVG that will be embedded directly into HTML, or when the Mermaid source is not fully trusted, select the sealed resvg-safe pipeline through optionsJson:

const svg = await engine.renderSvg(source, {
  optionsJson: JSON.stringify({ svg: { pipeline: "resvg-safe" } }),
});

The pipeline values are parity, readable, and resvg-safe. The safe pipeline does not provide browser Document or owner-document admission APIs; use @mermanjs/web* for browser DOM mounting.

The native package is the recommended choice when a supported platform binary is available. Use this package when a deployment target cannot load the native package or when a single portable Node artifact is more useful than native startup and throughput.