markdown/no-missing-link-fragments

[usage](#usage) jumps to the "Usage" heading in the same document. When the heading is renamed, the link stays and silently stops working.

A heading's anchor is computed the way GitHub does it: lowercased, punctuation removed, spaces turned into -, and -1, -2 added to repeats. An id or name attribute in HTML, a heading written in HTML and {#custom-id} at the end of a heading count too. #top and line references like #L10-L20 are always allowed.

Configure#

Off by default. It needs an ESLint config that says which files are in the language:

eslint.config.js

import markdown from "@eslint/markdown";

export default [
  {
    files: ["**/*.md"],
    plugins: { markdown },
    language: "markdown/commonmark",
    rules: { "markdown/no-missing-link-fragments": "error" },
  },
];

It also works with markdown/gfm.

Examples#

example.md1 problem

# Getting started

See [usage](#usage).

example.mdNo problems

# Getting started

See [the start](#getting-started), [the API](#api), [the FAQ](#questions) or [the top](#top).

## Reference {#api}

<a id="questions"></a>

Options#

Option	Default	What it does
`ignoreCase`	`true`	Ignore case, so `#Usage` matches the anchor `usage`.
`allowPattern`	`""`	A regular expression. Fragments that match it are not reported.

example.mdwith { "ignoreCase": false }1 problem

# Usage

See [usage](#Usage).

example.mdwith { "allowPattern": "^tab-" }No problems

See [the second tab](#tab-2).