rewrite.md

A programmable Markdown transformer for safe rewriting, dynamic injection, and front-matter processing

Installation

npm install rewrite.md
# or
pnpm add rewrite.md
# or
bun add rewrite.md

Usage

rewriteMdComment

Basic Example

import { rewriteMdComment } from 'rewrite.md';

const md = `
# Project

<!-- version:start -->
0.0.0
<!-- version:end -->

## License
MIT
`;

const result = rewriteMdComment(md, {
  version: '1.2.3',
});

console.log(result);

Output:

# Project

<!-- version:start -->

1.2.3

<!-- version:end -->

## License

MIT

Multiple Blocks

You can rewrite multiple sections at once:

const md = `
<!-- version:start -->0.0.0<!-- version:end -->
<!-- author:start -->unknown<!-- author:end -->
`;

const result = rewriteMdComment(md, {
  version: '2.0.0',
  author: 'TenE',
});

Custom Markers

Change the default start / end markers:

const md = `
<!-- stats:begin -->
old value
<!-- stats:finish -->
`;

const result = rewriteMdComment(
  md,
  { stats: '⭐ 120 stars' },
  {
    startMarker: 'begin',
    endMarker: 'finish',
  },
);

Buffer Support

If you pass a Buffer, the return type depends on preserveType.

const buffer = Buffer.from(`
<!-- build:start -->
pending
<!-- build:end -->
`);

const result = rewriteMdComment(buffer, { build: 'success' }, { preserveType: true });

console.log(Buffer.isBuffer(result)); // true

Real-World Example (Sync Monorepo Package List)

import fs from 'node:fs';
import { rewriteMdComment } from 'rewrite.md';

const packages = ['core', 'cli', 'plugin'];
const table = packages.map((p) => `- @myorg/${p}`).join('\n');
const readme = fs.readFileSync('README.md', 'utf8');
const updated = rewriteMdComment(readme, {
  packages: table,
});

fs.writeFileSync('README.md', updated);

Marker Format

Blocks must follow this structure:

<!-- key:start -->

content to replace

<!-- key:end -->

• key corresponds to a property in the data object
• start and end are configurable via options