@unifast/highlight

Overview

@unifast/highlight provides syntax highlighting powered by lowlight (a highlight.js wrapper). Unlike the built-in syntect() and treeSitter() plugins that run highlighting in Rust, this package applies highlighting as a JavaScript HAST transform after compilation — giving you access to highlight.js’s extensive language and theme ecosystem.

Installation

Quick Start

import { compile } from "@unifast/node";
import { highlight } from "@unifast/highlight";

const md = `
\`\`\`javascript
const x = 42;
console.log(x);
\`\`\`
`;

const result = compile(md, {
  plugins: [highlight()],
});

console.log(result.output);
// Code blocks are highlighted with highlight.js CSS classes

How It Works

1. The Rust compiler produces HAST output with un-highlighted <pre><code> blocks

2. The highlight() plugin’s hastTransform walks the HAST tree

3. For each <code> element with a language-* class, lowlight highlights the code

4. The highlighted HAST nodes replace the original children

Since this runs as a HAST transform, the native Rust highlighting (syntect / treeSitter) must be disabled. The plugin automatically sets highlight.enabled: false in compile options.

Exports Summary