@cutticat/md-url-map

Rewrite URL destinations in Markdown through a mapper. Relative links stay in git; pack turns them into GitFlic, GitHub, or GitLab URLs for npm. Inline images point at the raw file. Links and reference definitions stay on the blob page.

Table of Contents

• Overview
• Installation
• CLI
• Quick start
• API
• Documentation
• Requirements

Overview

map(markdown, mapper) walks [text](href), images, and reference definitions with micromark and calls mapper for each destination. Return the same string to leave it unchanged. Replacements are written as <url>. Code spans, fences, and the rest of the file stay as they are.

Compose with when(isRelative, toGitFlic({ ... })) so only file-relative hrefs (./a.md, docs/a.md) are rewritten. A link becomes a blob URL. An inline image (![alt](./logo.png)) becomes a raw URL, which npmjs can display. Hash, /rooted, //host, and https: are left alone. Other predicates: isAbsolute, isHash, isRootRelative, isProtocolRelative. toBase({ base }) resolves like a browser: new URL(href, base). The destination type is ignored there.

The md-url-map CLI is the same composition: map for one file (--host or --base), pack for a prepack hook that reads package.json repository and rewrites README.md.

Installation

pnpm i @cutticat/md-url-map

CLI

After install, the md-url-map binary is on PATH via pnpm exec. In this repository, pnpm run md-url-map map ….

map

Rewrite relative destinations in one file. Default: stdout.

Pass --base or --host, not both. --base resolves relative hrefs against a document URL (WHATWG new URL(href, base)). --host writes git blob URLs for links and raw URLs for inline images.

--file is the Markdown path from the git root (inferred from .git when you pass a real path). Required when reading stdin with --host. Unused with --base.

md-url-map map README.md --base https://example.com/docs/README.md
md-url-map map README.md --host gitflic --owner cutticat-npm --project uuids
md-url-map map README.md --host gitflic --owner cutticat-npm --project uuids -i
md-url-map map README.md --host github --owner acme --repo app -o out.md
md-url-map map README.md --host gitlab --project-path group/app --ref v1.0.0
cat README.md | md-url-map map - --file README.md --host gitflic --owner o --project p

pack

Read package.json repository in the current directory (or -C), rewrite README.md in place. Infers GitFlic / GitHub / GitLab from the URL. file for URL resolve is the README path from the git root (walks up to .git).

repository.url may be https://, git+https://, ssh://, git+ssh://, git://, or git@host:path. SSH and git:// remotes get an https:// origin. GitFlic HTTPS is /project/{owner}/{project}; the SSH clone git@gitflic.ru:owner/project works too.

An inline image becomes a raw URL on the same origin:

• GitHub: /{owner}/{repo}/raw/{ref}/{path}
• GitLab: /{project}/-/raw/{ref}/{path}
• GitFlic: /project/{owner}/{project}/blob/raw?branch={ref}&file={path}

A link to the same file stays a blob URL. So does a reference definition ([id]: ./logo.png): one definition is shared by links and images.

Use from prepack. Restore the working tree in postpack yourself (git checkout -- README.md). This package does that for its own README.

md-url-map pack
md-url-map pack -C ./packages/plugin --ref main

Quick start

import { isRelative, map, toBase, toGitFlic, when } from "@cutticat/md-url-map"

map(
  markdown,
  when(
    isRelative,
    toGitFlic({
      owner: "cutticat-npm",
      project: "uuids",
      ref: "main",
      file: "README.md",
    })
  )
)

map(markdown, when(isRelative, toBase({ base: "https://example.com/docs/README.md" })))

import { map } from "@cutticat/md-url-map"

map("[site](https://old.example)", href =>
  href === "https://old.example" ? "https://new.example" : href
)
// [site](<https://new.example>)

API

• map(markdown, mapper) — walk destinations, return a new string
• when(predicate, mapper) — run mapper only when predicate is true
• isAbsolute(href) — scheme URLs (https:, mailto:)
• isHash(href) — hash-only (#overview)
• isProtocolRelative(href) — protocol-relative (//cdn.example/x)
• isRelative(href) — file-relative destinations (./a.md, docs/a.md)
• isRootRelative(href) — root-relative (/docs/a.md)
• toBase({ base }) — new URL(href, base) (document URL)
• toGitFlic({ owner, project, ref, file, origin? })
• toGitHub({ owner, repo, ref, file, origin? })
• toGitLab({ projectPath, ref, file, origin? })
• HrefType — "image" for ![alt](href), "other" for links and definitions
• HrefMapper — (href, type) => string
• HrefPredicate — (href, type) => boolean

file is the Markdown path from the git root (README.md, packages/plugin/README.md).

Replacements use source offsets. Surrounding Markdown is not reformatted.

Documentation

• Project structure
• Scripts
• Style guide
• Contributing

Requirements

• Node.js >= 22.18.0
• pnpm >= 10.17.0
• TypeScript >= 5.9.0