docs: markdownItFactory is not necessary

Ref: https://github.com/theoludwig/markdownlint-rule-relative-links/issues/13

.commitlintrc.json

@@ -1 +0,0 @@
-{ "extends": ["@commitlint/config-conventional"] }

.eslintrc.json

@@ -1,7 +0,0 @@
-{
-  "extends": ["conventions", "prettier"],
-  "plugins": ["prettier"],
-  "rules": {
-    "prettier/prettier": "error"
-  }
-}

.github/workflows/lint.yml

@@ -4,16 +4,16 @@ on:
   push:
     branches: [develop]
   pull_request:
-    branches: [master, develop]
+    branches: [main, develop]
 
 jobs:
   lint:
     runs-on: "ubuntu-latest"
     steps:
-      - uses: "actions/checkout@v4.1.1"
+      - uses: "actions/checkout@v4.2.2"
 
       - name: "Setup Node.js"
-        uses: "actions/setup-node@v4.0.1"
+        uses: "actions/setup-node@v4.1.0"
         with:
           node-version: "lts/*"
           cache: "npm"
@@ -21,9 +21,15 @@ jobs:
       - name: "Install dependencies"
         run: "npm clean-install"
 
-      - run: 'npm run lint:commit -- --to "${{ github.sha }}"'
-      - run: "npm run lint:editorconfig"
-      - run: "npm run lint:markdown"
-      - run: "npm run lint:eslint"
-      - run: "npm run lint:prettier"
-      - run: "npm run lint:javascript"
+      - run: "node --run lint:editorconfig"
+      - run: "node --run lint:markdown"
+      - run: "node --run lint:eslint"
+      - run: "node --run lint:prettier"
+      - run: "node --run lint:typescript"
+
+  commitlint:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: "actions/checkout@v4.2.2"
+
+      - uses: "wagoid/commitlint-github-action@v6.2.0"

.github/workflows/release.yml

@@ -2,7 +2,7 @@ name: "Release"
 
 on:
   push:
-    branches: [master]
+    branches: [main]
 
 jobs:
   release:
@@ -13,13 +13,13 @@ jobs:
       pull-requests: "write"
       id-token: "write"
     steps:
-      - uses: "actions/checkout@v4.1.1"
+      - uses: "actions/checkout@v4.2.2"
         with:
           fetch-depth: 0
           persist-credentials: false
 
       - name: "Setup Node.js"
-        uses: "actions/setup-node@v4.0.1"
+        uses: "actions/setup-node@v4.1.0"
         with:
           node-version: "lts/*"
           cache: "npm"
@@ -31,7 +31,7 @@ jobs:
         run: "npm audit signatures"
 
       - name: "Release"
-        run: "npm run release"
+        run: "node --run release"
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/test.yml

@@ -4,16 +4,16 @@ on:
   push:
     branches: [develop]
   pull_request:
-    branches: [master, develop]
+    branches: [main, develop]
 
 jobs:
   test:
     runs-on: "ubuntu-latest"
     steps:
-      - uses: "actions/checkout@v4.1.1"
+      - uses: "actions/checkout@v4.2.2"
 
       - name: "Setup Node.js"
-        uses: "actions/setup-node@v4.0.1"
+        uses: "actions/setup-node@v4.1.0"
         with:
           node-version: "lts/*"
           cache: "npm"
@@ -22,4 +22,4 @@ jobs:
         run: "npm clean-install"
 
       - name: "Test"
-        run: "npm run test"
+        run: "node --run test"

.gitignore

@@ -20,10 +20,6 @@ npm-debug.log*
 
 # IDE - VSCode
 .vscode/*
-!.vscode/settings.json
-!.vscode/tasks.json
-!.vscode/launch.json
-!.vscode/extensions.json
 
 # misc
 .DS_Store

.husky/commit-msg

@@ -1,4 +0,0 @@
-#!/bin/sh
-. "$(dirname "$0")/_/husky.sh"
-
-npm run lint:commit -- --edit

.husky/pre-commit

@@ -1,6 +0,0 @@
-#!/bin/sh
-. "$(dirname "$0")/_/husky.sh"
-
-npm run lint:staged
-npm run lint:javascript
-npm run test

.lintstagedrc.json

@@ -1,6 +0,0 @@
-{
-  "*": ["editorconfig-checker"],
-  "*.{js,jsx,ts,tsx}": ["prettier --write", "eslint --fix"],
-  "*.{json,jsonc,yml,yaml}": ["prettier --write"],
-  "*.{md,mdx}": ["prettier --write", "markdownlint-cli2 --fix"]
-}

.markdownlint-cli2.jsonc

@@ -1,11 +0,0 @@
-{
-  "config": {
-    "extends": "markdownlint/style/prettier",
-    "relative-links": true,
-    "default": true,
-    "MD033": false
-  },
-  "globs": ["**/*.{md,mdx}"],
-  "ignores": ["**/node_modules", "**/test/fixtures/**"],
-  "customRules": ["./src/index.js"]
-}

.markdownlint-cli2.mjs

@@ -0,0 +1,15 @@
+import relativeLinksRule from "./src/index.js"
+
+const config = {
+  config: {
+    extends: "markdownlint/style/prettier",
+    default: true,
+    "relative-links": true,
+    "no-inline-html": false,
+  },
+  globs: ["**/*.md"],
+  ignores: ["**/node_modules", "**/test/fixtures/**"],
+  customRules: [relativeLinksRule],
+}
+
+export default config

.npmrc

@@ -1,2 +1,2 @@
-save-exact=true
-provenance=true
+save-exact = true
+provenance = true

.releaserc.json

@@ -1,18 +1,8 @@
 {
-  "branches": ["master"],
+  "branches": ["main", { "name": "beta", "prerelease": true }],
   "plugins": [
-    [
-      "@semantic-release/commit-analyzer",
-      {
-        "preset": "conventionalcommits"
-      }
-    ],
-    [
-      "@semantic-release/release-notes-generator",
-      {
-        "preset": "conventionalcommits"
-      }
-    ],
+    "@semantic-release/commit-analyzer",
+    "@semantic-release/release-notes-generator",
     "@semantic-release/npm",
     "@semantic-release/github"
   ]

.vscode/extensions.json

@@ -1,8 +0,0 @@
-{
-  "recommendations": [
-    "editorconfig.editorconfig",
-    "esbenp.prettier-vscode",
-    "dbaeumer.vscode-eslint",
-    "davidanson.vscode-markdownlint"
-  ]
-}

.vscode/settings.json

@@ -1,8 +0,0 @@
-{
-  "editor.defaultFormatter": "esbenp.prettier-vscode",
-  "prettier.configPath": ".prettierrc.json",
-  "editor.formatOnSave": true,
-  "editor.codeActionsOnSave": {
-    "source.fixAll": "explicit"
-  }
-}

LICENSE

@@ -1,6 +1,6 @@
 # MIT License
 
-Copyright (c) Théo LUDWIG
+Copyright (c) Théo LUDWIG <contact@theoludwig.fr>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -10,7 +10,7 @@
   <a href="./CODE_OF_CONDUCT.md"><img src="https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg" alt="Contributor Covenant" /></a>
   <br />
   <a href="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/lint.yml"><img src="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/lint.yml/badge.svg?branch=develop" alt="Lint" /></a>
-  <a href="https://github.com/theoludwig/markdownlint-rule-relative-linksactions/workflows/test.yml"><img src="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/test.yml/badge.svg?branch=develop" alt="Test" /></a>
+  <a href="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/test.yml"><img src="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/test.yml/badge.svg?branch=develop" alt="Test" /></a>
   <br />
   <a href="https://conventionalcommits.org"><img src="https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg" alt="Conventional Commits" /></a>
   <a href="https://github.com/semantic-release/semantic-release"><img src="https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg" alt="semantic-release" /></a>
@@ -49,13 +49,12 @@ awesome.md:3 relative-links Relative links should be valid ["./invalid.txt" shou
 ### Additional features
 
 - Support images (e.g: `![Image](./image.png)`).
-- Support anchors (heading fragment links) (e.g: `[Link](./awesome.md#existing-heading)`).
+- Support links fragments similar to the [built-in `markdownlint` rule - MD051](https://github.com/DavidAnson/markdownlint/blob/main/doc/md051.md) (e.g: `[Link](./awesome.md#heading)`).
 - Ignore external links and absolute paths as it only checks relative links (e.g: `https://example.com/` or `/absolute/path.png`).
 
 ### Limitations
 
-- Only images and links defined using markdown syntax are supported, html syntax is not supported (e.g: `<a href="./link.txt" />` or `<img src="./image.png" />`).
-- Anchors checking is limited to headings, other elements are not supported (e.g: with a "id", `<div id="anchor" />`).
+- Only images and links defined using markdown syntax are validated, html syntax is ignored (e.g: `<a href="./link.txt" />` or `<img src="./image.png" />`).
 
 Contributions are welcome to improve the rule, and to alleviate these limitations. See [CONTRIBUTING.md](./CONTRIBUTING.md) for more information.
 
@@ -67,7 +66,7 @@ Contributions are welcome to improve the rule, and to alleviate these limitation
 
 ## Prerequisites
 
-- [Node.js](https://nodejs.org/) >= 16.0.0
+[Node.js](https://nodejs.org/) >= 22.0.0
 
 ## Installation
 
@@ -81,18 +80,22 @@ There are various ways [markdownlint](https://github.com/DavidAnson/markdownlint
 
 We recommend configuring [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2) over [markdownlint-cli](https://github.com/igorshubovych/markdownlint-cli) for compatibility with the [vscode-markdownlint](https://github.com/DavidAnson/vscode-markdownlint) extension.
 
-`.markdownlint-cli2.jsonc`
+`.markdownlint-cli2.mjs`
 
-```json
-{
-  "config": {
-    "default": true,
-    "relative-links": true
+```js
+import relativeLinksRule from "markdownlint-rule-relative-links"
+
+const config = {
+  config: {
+    default: true,
+    "relative-links": true,
   },
-  "globs": ["**/*.{md,mdx}"],
-  "ignores": ["**/node_modules"],
-  "customRules": ["markdownlint-rule-relative-links"]
+  globs: ["**/*.md"],
+  ignores: ["**/node_modules"],
+  customRules: [relativeLinksRule],
 }
+
+export default config
 ```
 
 `package.json`
@@ -108,7 +111,7 @@ We recommend configuring [markdownlint-cli2](https://github.com/DavidAnson/markd
 ## Usage
 
 ```sh
-npm run lint:markdown
+node --run lint:markdown
 ```
 
 ## 💡 Contributing

eslint.config.js

@@ -0,0 +1,13 @@
+import typescriptESLint from "typescript-eslint"
+import configConventions from "eslint-config-conventions"
+
+export default typescriptESLint.config(...configConventions, {
+  files: ["**/*.ts", "**/*.tsx"],
+  languageOptions: {
+    parser: typescriptESLint.parser,
+    parserOptions: {
+      projectService: true,
+      tsconfigRootDir: import.meta.dirname,
+    },
+  },
+})

package.json

@@ -18,6 +18,8 @@
     "markdownlint-rule"
   ],
   "main": "src/index.js",
+  "types": "src/index.d.ts",
+  "type": "module",
   "files": [
     "src"
   ],
@@ -26,46 +28,35 @@
     "provenance": true
   },
   "engines": {
-    "node": ">=16.0.0",
-    "npm": ">=9.0.0"
+    "node": ">=22.0.0"
   },
   "scripts": {
-    "lint:commit": "commitlint",
     "lint:editorconfig": "editorconfig-checker",
     "lint:markdown": "markdownlint-cli2",
-    "lint:eslint": "eslint . --max-warnings 0 --report-unused-disable-directives --ignore-path .gitignore",
-    "lint:prettier": "prettier . --check --ignore-path .gitignore",
-    "lint:javascript": "tsc --project jsconfig.json --noEmit",
-    "lint:staged": "lint-staged",
-    "test": "node --test --experimental-test-coverage ./test",
-    "release": "semantic-release",
-    "postinstall": "husky install",
-    "prepublishOnly": "pinst --disable",
-    "postpublish": "pinst --enable"
+    "lint:eslint": "eslint . --max-warnings 0",
+    "lint:prettier": "prettier . --check",
+    "lint:typescript": "tsc --noEmit",
+    "test": "node --test",
+    "release": "semantic-release"
   },
   "dependencies": {
-    "markdown-it": "14.0.0"
+    "markdown-it": "14.1.0"
   },
   "devDependencies": {
-    "@commitlint/cli": "18.4.4",
-    "@commitlint/config-conventional": "18.4.4",
-    "@types/markdown-it": "13.0.7",
-    "@types/node": "20.10.8",
-    "editorconfig-checker": "5.1.2",
-    "eslint": "8.56.0",
-    "eslint-config-conventions": "13.1.0",
-    "eslint-config-prettier": "9.1.0",
-    "eslint-plugin-import": "2.29.1",
-    "eslint-plugin-prettier": "5.1.2",
-    "eslint-plugin-promise": "6.1.1",
-    "eslint-plugin-unicorn": "50.0.1",
-    "husky": "8.0.3",
-    "lint-staged": "15.2.0",
-    "markdownlint": "0.33.0",
-    "markdownlint-cli2": "0.11.0",
-    "pinst": "3.0.0",
-    "prettier": "3.1.1",
-    "semantic-release": "22.0.12",
-    "typescript": "5.3.3"
+    "@types/markdown-it": "14.1.2",
+    "@types/node": "22.15.17",
+    "editorconfig-checker": "6.0.1",
+    "eslint": "9.26.0",
+    "eslint-config-conventions": "19.2.0",
+    "eslint-plugin-promise": "7.2.1",
+    "eslint-plugin-unicorn": "59.0.1",
+    "eslint-plugin-import-x": "4.11.1",
+    "globals": "16.1.0",
+    "markdownlint": "0.38.0",
+    "markdownlint-cli2": "0.18.0",
+    "prettier": "3.5.3",
+    "semantic-release": "24.2.3",
+    "typescript-eslint": "8.32.0",
+    "typescript": "5.8.3"
   }
 }

src/index.d.ts

@@ -0,0 +1,8 @@
+import type MarkdownIt from "markdown-it"
+import type { Rule } from "markdownlint"
+
+declare const relativeLinksRule: Rule
+export default relativeLinksRule
+
+declare const markdownIt: MarkdownIt
+export { markdownIt }

src/index.js

@@ -1,23 +1,29 @@
-"use strict"
+import { pathToFileURL } from "node:url"
+import fs from "node:fs"
 
-const { pathToFileURL } = require("node:url")
-const fs = require("node:fs")
-
-const {
-  filterTokens,
+import { filterTokens } from "./markdownlint-rule-helpers/helpers.js"
+import {
   convertHeadingToHTMLFragment,
   getMarkdownHeadings,
-} = require("./utils.js")
+  getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
+  lineFragmentRe,
+} from "./utils.js"
+
+export { markdownIt } from "./utils.js"
 
 /** @typedef {import('markdownlint').Rule} MarkdownLintRule */
 
 /**
  * @type {MarkdownLintRule}
  */
-const customRule = {
+const relativeLinksRule = {
   names: ["relative-links"],
   description: "Relative links should be valid",
   tags: ["links"],
+  parser: "markdownit",
   function: (params, onError) => {
     filterTokens(params, "inline", (token) => {
       const children = token.children ?? []
@@ -45,50 +51,125 @@ const customRule = {
           }
         }
 
-        if (hrefSrc != null) {
-          const url = new URL(hrefSrc, pathToFileURL(params.name))
-          const isRelative =
-            url.protocol === "file:" && !hrefSrc.startsWith("/")
-          if (isRelative) {
-            const detail = `"${hrefSrc}"`
+        if (hrefSrc == null) {
+          continue
+        }
 
-            if (!fs.existsSync(url)) {
+        const url = new URL(hrefSrc, pathToFileURL(params.name))
+        const isRelative =
+          url.protocol === "file:" &&
+          !hrefSrc.startsWith("/") &&
+          !hrefSrc.startsWith("#")
+
+        if (!isRelative) {
+          continue
+        }
+
+        const detail = `"${hrefSrc}"`
+
+        if (!fs.existsSync(url)) {
+          onError({
+            lineNumber,
+            detail: `${detail} should exist in the file system`,
+          })
+          continue
+        }
+
+        if (url.hash.length <= 0) {
+          if (hrefSrc.includes("#")) {
+            if (type === "image") {
               onError({
                 lineNumber,
-                detail: `${detail} should exist in the file system`,
+                detail: `${detail} should not have a fragment identifier as it is an image`,
               })
               continue
             }
 
-            if (type === "link_open" && url.hash !== "") {
-              const fileContent = fs.readFileSync(url, { encoding: "utf8" })
-              const headings = getMarkdownHeadings(fileContent)
-
-              /** @type {Map<string, number>} */
-              const fragments = new Map()
-
-              const headingsHTMLFragments = headings.map((heading) => {
-                const fragment = convertHeadingToHTMLFragment(heading)
-                const count = fragments.get(fragment) ?? 0
-                fragments.set(fragment, count + 1)
-                if (count !== 0) {
-                  return `${fragment}-${count}`
-                }
-                return fragment
-              })
-
-              if (!headingsHTMLFragments.includes(url.hash)) {
-                onError({
-                  lineNumber,
-                  detail: `${detail} should have a valid fragment identifier`,
-                })
-              }
-            }
+            onError({
+              lineNumber,
+              detail: `${detail} should have a valid fragment identifier`,
+            })
+            continue
           }
+          continue
+        }
+
+        if (type === "image") {
+          onError({
+            lineNumber,
+            detail: `${detail} should not have a fragment identifier as it is an image`,
+          })
+          continue
+        }
+
+        if (!url.pathname.endsWith(".md")) {
+          continue
+        }
+
+        const fileContent = fs.readFileSync(url, { encoding: "utf8" })
+        const headings = getMarkdownHeadings(fileContent)
+        const idOrAnchorNameHTMLFragments =
+          getMarkdownIdOrAnchorNameFragments(fileContent)
+
+        /** @type {Map<string, number>} */
+        const fragments = new Map()
+
+        const fragmentsHTML = headings.map((heading) => {
+          const fragment = convertHeadingToHTMLFragment(heading)
+          const count = fragments.get(fragment) ?? 0
+          fragments.set(fragment, count + 1)
+          if (count !== 0) {
+            return `${fragment}-${count}`
+          }
+          return fragment
+        })
+
+        fragmentsHTML.push(...idOrAnchorNameHTMLFragments)
+
+        if (!fragmentsHTML.includes(url.hash)) {
+          if (url.hash.startsWith("#L")) {
+            const lineNumberFragmentString = getLineNumberStringFromFragment(
+              url.hash,
+            )
+
+            const hasOnlyDigits = isValidIntegerString(lineNumberFragmentString)
+            if (!hasOnlyDigits) {
+              if (lineFragmentRe.test(url.hash)) {
+                continue
+              }
+
+              onError({
+                lineNumber,
+                detail: `${detail} should have a valid fragment identifier`,
+              })
+              continue
+            }
+
+            const lineNumberFragment = Number.parseInt(
+              lineNumberFragmentString,
+              10,
+            )
+            const numberOfLines = getNumberOfLines(fileContent)
+            if (lineNumberFragment > numberOfLines) {
+              onError({
+                lineNumber,
+                detail: `${detail} should have a valid fragment identifier, ${detail} should have at least ${lineNumberFragment} lines to be valid`,
+              })
+              continue
+            }
+
+            continue
+          }
+
+          onError({
+            lineNumber,
+            detail: `${detail} should have a valid fragment identifier`,
+          })
+          continue
         }
       }
     })
   },
 }
 
-module.exports = customRule
+export default relativeLinksRule

src/markdownlint-rule-helpers/helpers.js

@@ -0,0 +1,33 @@
+/**
+ * Dependency Vendoring of `markdownlint-rule-helpers`
+ * @see https://www.npmjs.com/package/markdownlint-rule-helpers
+ */
+
+/** @typedef {import('markdownlint').RuleParams} MarkdownLintRuleParams */
+/** @typedef {import('markdownlint').MarkdownItToken} MarkdownItToken */
+
+/**
+ * Calls the provided function for each matching token.
+ *
+ * @param {MarkdownLintRuleParams} params RuleParams instance.
+ * @param {string} type Token type identifier.
+ * @param {(token: MarkdownItToken) => void} handler Callback function.
+ * @returns {void}
+ */
+export const filterTokens = (params, type, handler) => {
+  for (const token of params.parsers.markdownit.tokens) {
+    if (token.type === type) {
+      handler(token)
+    }
+  }
+}
+
+/**
+ * Gets a Regular Expression for matching the specified HTML attribute.
+ *
+ * @param {string} name HTML attribute name.
+ * @returns {RegExp} Regular Expression for matching.
+ */
+export const getHtmlAttributeRe = (name) => {
+  return new RegExp(`\\s${name}\\s*=\\s*['"]?([^'"\\s>]*)`, "iu")
+}

src/utils.js

@@ -1,23 +1,10 @@
-const MarkdownIt = require("markdown-it")
+import MarkdownIt from "markdown-it"
 
-/** @typedef {import('markdownlint').RuleParams} MarkdownLintRuleParams */
-/** @typedef {import('markdownlint').MarkdownItToken} MarkdownItToken */
+import { getHtmlAttributeRe } from "./markdownlint-rule-helpers/helpers.js"
 
-/**
- * Calls the provided function for each matching token.
- *
- * @param {MarkdownLintRuleParams} params RuleParams instance.
- * @param {string} type Token type identifier.
- * @param {(token: MarkdownItToken) => void} handler Callback function.
- * @returns {void}
- */
-const filterTokens = (params, type, handler) => {
-  for (const token of params.tokens) {
-    if (token.type === type) {
-      handler(token)
-    }
-  }
-}
+export const markdownIt = new MarkdownIt({ html: true })
+
+export const lineFragmentRe = /^#(?:L\d+(?:C\d+)?-L\d+(?:C\d+)?|L\d+)$/
 
 /**
  * Converts a Markdown heading into an HTML fragment according to the rules
@@ -27,7 +14,7 @@ const filterTokens = (params, type, handler) => {
  * @param {string} inlineText Inline token for heading.
  * @returns {string} Fragment string for heading.
  */
-const convertHeadingToHTMLFragment = (inlineText) => {
+export const convertHeadingToHTMLFragment = (inlineText) => {
   return (
     "#" +
     encodeURIComponent(
@@ -53,8 +40,7 @@ const ignoredTokens = new Set(["heading_open", "heading_close"])
  * @param {string} content
  * @returns {string[]}
  */
-const getMarkdownHeadings = (content) => {
-  const markdownIt = new MarkdownIt({ html: true })
+export const getMarkdownHeadings = (content) => {
   const tokens = markdownIt.parse(content, {})
 
   /** @type {string[]} */
@@ -94,8 +80,74 @@ const getMarkdownHeadings = (content) => {
   return headings
 }
 
-module.exports = {
-  filterTokens,
-  convertHeadingToHTMLFragment,
-  getMarkdownHeadings,
+const nameHTMLAttributeRegex = getHtmlAttributeRe("name")
+const idHTMLAttributeRegex = getHtmlAttributeRe("id")
+
+/**
+ * Gets the id or anchor name fragments from a Markdown string.
+ * @param {string} content
+ * @returns {string[]}
+ */
+export const getMarkdownIdOrAnchorNameFragments = (content) => {
+  const tokens = markdownIt.parse(content, {})
+
+  /** @type {string[]} */
+  const result = []
+
+  for (const token of tokens) {
+    const regexMatch =
+      idHTMLAttributeRegex.exec(token.content) ||
+      nameHTMLAttributeRegex.exec(token.content)
+    if (regexMatch == null) {
+      continue
+    }
+
+    const idOrName = regexMatch[1]
+    if (idOrName == null || idOrName.length <= 0) {
+      continue
+    }
+
+    const htmlFragment = "#" + idOrName
+    if (!result.includes(htmlFragment)) {
+      result.push(htmlFragment)
+    }
+  }
+
+  return result
+}
+
+/**
+ * Checks if a string is a valid integer.
+ *
+ * Using `Number.parseInt` combined with `Number.isNaN` will not be sufficient enough because `Number.parseInt("1abc", 10)` will return `1` (a valid number) instead of `NaN`.
+ *
+ * @param {string} value
+ * @returns {boolean}
+ * @example isValidIntegerString("1") // true
+ * @example isValidIntegerString("45") // true
+ * @example isValidIntegerString("1abc") // false
+ * @example isValidIntegerString("1.0") // false
+ */
+export const isValidIntegerString = (value) => {
+  const regex = /^\d+$/
+  return regex.test(value)
+}
+
+/**
+ * Gets the number of lines in a string, based on the number of `\n` characters.
+ * @param {string} content
+ * @returns {number}
+ */
+export const getNumberOfLines = (content) => {
+  return content.split("\n").length
+}
+
+/**
+ * Gets the line number string from a fragment.
+ * @param {string} fragment
+ * @returns {string}
+ * @example getLineNumberStringFromFragment("#L50") // 50
+ */
+export const getLineNumberStringFromFragment = (fragment) => {
+  return fragment.slice(2)
 }

test/fixtures/invalid/empty-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id>Content</div>

test/fixtures/invalid/empty-id-fragment/empty-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#)

test/fixtures/invalid/ignore-empty-fragment-checking-for-image.md

@@ -0,0 +1,3 @@
+# Invalid
+
+![Image](../image.png#)

test/fixtures/invalid/ignore-fragment-checking-for-image.md

@@ -0,0 +1,3 @@
+# Invalid
+
+![Image](../image.png#non-existing-fragment)

test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<input name="name-should-be-ignored" id="id-after-name" />

test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/ignore-name-fragment-if-not-an-anchor.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Invalid](./awesome.md#name-should-be-ignored)

test/fixtures/invalid/ignore-not-an-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div data-id="not-an-id-should-be-ignored">Content</div>

test/fixtures/invalid/ignore-not-an-id-fragment/ignore-not-an-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Invalid](./awesome.md#not-an-id-should-be-ignored)

test/fixtures/invalid/invalid-heading-case-sensitive/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Existing Heading

test/fixtures/invalid/invalid-heading-case-sensitive/invalid-heading-case-sensitive.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#ExistIng-Heading)

test/fixtures/invalid/invalid-heading-with-L-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7abc)

test/fixtures/invalid/invalid-line-column-range-number-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-line-column-range-number-fragment/invalid-line-column-range-number-fragment.md

@@ -0,0 +1,31 @@
+# Invalid
+
+[Invalid](./awesome.md#L12-not-a-line-link)
+
+[Invalid](./awesome.md#l7)
+
+[Invalid](./awesome.md#L)
+
+[Invalid](./awesome.md#L7extra)
+
+[Invalid](./awesome.md#L30C)
+
+[Invalid](./awesome.md#L30Cextra)
+
+[Invalid](./awesome.md#L30L12)
+
+[Invalid](./awesome.md#L30C12)
+
+[Invalid](./awesome.md#L30C11-)
+
+[Invalid](./awesome.md#L30C11-L)
+
+[Invalid](./awesome.md#L30C11-L31C)
+
+[Invalid](./awesome.md#L30C11-C31)
+
+[Invalid](./awesome.md#C30)
+
+[Invalid](./awesome.md#C11-C31)
+
+[Invalid](./awesome.md#C11-L4C31)

test/fixtures/invalid/invalid-line-number-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7)

test/fixtures/invalid/non-existing-anchor-name-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<a name="existing-heading-anchor">Link</a>

test/fixtures/invalid/non-existing-anchor-name-fragment/non-existing-anchor-name-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#non-existing-anchor-name-fragment)

test/fixtures/invalid/non-existing-element-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id="existing-element-id-fragment">Content</div>

test/fixtures/invalid/non-existing-element-id-fragment/non-existing-element-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#non-existing-element-id-fragment)

test/fixtures/invalid/non-existing-heading-fragment/awesome.md

@@ -1,3 +1,3 @@
-# Valid
+# Awesome
 
 ## Existing Heading

test/fixtures/valid/existing-anchor-name-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<a name="existing-heading-anchor">Link</a>

test/fixtures/valid/existing-anchor-name-fragment/existing-anchor-name-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#existing-heading-anchor)

test/fixtures/valid/existing-element-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id="existing-element-id-fragment">Content</div>

test/fixtures/valid/existing-element-id-fragment/existing-element-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#existing-element-id-fragment)

test/fixtures/valid/existing-heading-fragment/awesome.md

@@ -1,4 +1,4 @@
-# Valid
+# Awesome
 
 ## Existing Heading
 

test/fixtures/valid/existing-heading-with-accents/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Développement

test/fixtures/valid/existing-heading-with-accents/existing-heading-with-accents.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#développement)

test/fixtures/valid/existing-image.md

@@ -1,3 +1,3 @@
 # Valid
 
-![Image](./image.png)
+![Image](../image.png)

test/fixtures/valid/ignore-fragment-checking-in-own-file.md

@@ -0,0 +1,5 @@
+# Valid
+
+<div id="existing-element-id-fragment">Content</div>
+
+[Link fragment](#non-existing-element-id-fragment)

test/fixtures/valid/only-parse-markdown-files-for-fragments/awesome.html

@@ -0,0 +1,9 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Awesome</title>
+  </head>
+  <body></body>
+</html>

test/fixtures/valid/only-parse-markdown-files-for-fragments/only-parse-markdown-files-for-fragments.md

@@ -0,0 +1,7 @@
+# Valid
+
+[Link fragment HTML](./awesome.html#existing-heading)
+
+[Link fragment TXT](./abc.txt#existing-heading)
+
+[Link fragment Image](../../image.png#existing-heading)

test/fixtures/valid/valid-heading-like-number-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## L7

test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#l7)

test/fixtures/valid/valid-line-column-range-number-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## L12 Not A Line Link

test/fixtures/valid/valid-line-column-range-number-fragment/valid-line-column-range-number-fragment.md

@@ -0,0 +1,11 @@
+# Valid
+
+[Valid](./awesome.md#l12-not-a-line-link)
+
+[Valid](./awesome.md#L30-L31)
+
+[Valid](./awesome.md#L3C24-L88)
+
+[Valid](./awesome.md#L304-L314C98)
+
+[Valid](./awesome.md#L200C4-L3244C2)

test/fixtures/valid/valid-line-number-fragment/awesome.md

@@ -0,0 +1,9 @@
+# Awesome
+
+ABC
+
+Line 5
+
+Line 7 Text
+
+## L7

test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment line number 7](./awesome.md#L7)

test/index.test.js

@@ -1,9 +1,9 @@
-const { test } = require("node:test")
-const assert = require("node:assert/strict")
+import { test } from "node:test"
+import assert from "node:assert/strict"
 
-const { markdownlint } = require("markdownlint").promises
+import * as markdownlint from "markdownlint/promise"
 
-const relativeLinksRule = require("../src/index.js")
+import relativeLinksRule, { markdownIt } from "../src/index.js"
 
 /**
  *
@@ -11,102 +11,240 @@ const relativeLinksRule = require("../src/index.js")
  * @returns
  */
 const validateMarkdownLint = async (fixtureFile) => {
-  const lintResults = await markdownlint({
+  const lintResults = await markdownlint.lint({
     files: [fixtureFile],
     config: {
       default: false,
       "relative-links": true,
     },
     customRules: [relativeLinksRule],
+    markdownItFactory: () => {
+      return markdownIt
+    },
   })
   return lintResults[fixtureFile]
 }
 
 test("ensure the rule validates correctly", async (t) => {
-  await t.test("should be valid", async (t) => {
-    await t.test("with an existing heading fragment", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/valid/existing-heading-fragment/existing-heading-fragment.md",
-      )
-      assert.equal(lintResults?.length, 0)
-    })
+  await t.test("should be invalid", async (t) => {
+    const testCases = [
+      {
+        name: "should be invalid with an empty id fragment",
+        fixturePath:
+          "test/fixtures/invalid/empty-id-fragment/empty-id-fragment.md",
+        errors: ['"./awesome.md#" should have a valid fragment identifier'],
+      },
+      {
+        name: "should be invalid with a name fragment other than for an anchor",
+        fixturePath:
+          "test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/ignore-name-fragment-if-not-an-anchor.md",
+        errors: [
+          '"./awesome.md#name-should-be-ignored" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing id fragment (data-id !== id)",
+        fixturePath:
+          "test/fixtures/invalid/ignore-not-an-id-fragment/ignore-not-an-id-fragment.md",
+        errors: [
+          '"./awesome.md#not-an-id-should-be-ignored" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with uppercase letters in fragment (case sensitive)",
+        fixturePath:
+          "test/fixtures/invalid/invalid-heading-case-sensitive/invalid-heading-case-sensitive.md",
+        errors: [
+          '"./awesome.md#ExistIng-Heading" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with invalid heading with #L fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md",
+        errors: [
+          '"./awesome.md#L7abc" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a invalid line column range number fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-line-column-range-number-fragment/invalid-line-column-range-number-fragment.md",
+        errors: [
+          '"./awesome.md#L12-not-a-line-link" should have a valid fragment identifier',
+          '"./awesome.md#l7" should have a valid fragment identifier',
+          '"./awesome.md#L" should have a valid fragment identifier',
+          '"./awesome.md#L7extra" should have a valid fragment identifier',
+          '"./awesome.md#L30C" should have a valid fragment identifier',
+          '"./awesome.md#L30Cextra" should have a valid fragment identifier',
+          '"./awesome.md#L30L12" should have a valid fragment identifier',
+          '"./awesome.md#L30C12" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-L" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-L31C" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-C31" should have a valid fragment identifier',
+          '"./awesome.md#C30" should have a valid fragment identifier',
+          '"./awesome.md#C11-C31" should have a valid fragment identifier',
+          '"./awesome.md#C11-L4C31" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a invalid line number fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md",
+        errors: [
+          '"./awesome.md#L7" should have a valid fragment identifier, "./awesome.md#L7" should have at least 7 lines to be valid',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing anchor name fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-anchor-name-fragment/non-existing-anchor-name-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-anchor-name-fragment" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing element id fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-element-id-fragment/non-existing-element-id-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-element-id-fragment" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing heading fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-heading-fragment/non-existing-heading-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-heading" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a link to an image with a empty fragment",
+        fixturePath:
+          "test/fixtures/invalid/ignore-empty-fragment-checking-for-image.md",
+        errors: [
+          '"../image.png#" should not have a fragment identifier as it is an image',
+        ],
+      },
+      {
+        name: "should be invalid with a link to an image with a fragment",
+        fixturePath:
+          "test/fixtures/invalid/ignore-fragment-checking-for-image.md",
+        errors: [
+          '"../image.png#non-existing-fragment" should not have a fragment identifier as it is an image',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing file",
+        fixturePath: "test/fixtures/invalid/non-existing-file.md",
+        errors: ['"./index.test.js" should exist in the file system'],
+      },
+      {
+        name: "should be invalid with a non-existing image",
+        fixturePath: "test/fixtures/invalid/non-existing-image.md",
+        errors: ['"./image.png" should exist in the file system'],
+      },
+    ]
 
-    await t.test("with an existing file", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/valid/existing-file.md",
-      )
-      assert.equal(lintResults?.length, 0)
-    })
-
-    await t.test("with an existing image", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/valid/existing-image.md",
-      )
-      assert.equal(lintResults?.length, 0)
-    })
-
-    await t.test("should ignore absolute paths", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/valid/ignore-absolute-paths.md",
-      )
-      assert.equal(lintResults?.length, 0)
-    })
-
-    await t.test("should ignore external links", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/valid/ignore-external-links.md",
-      )
-      assert.equal(lintResults?.length, 0)
-    })
+    for (const { name, fixturePath, errors } of testCases) {
+      await t.test(name, async () => {
+        const lintResults = (await validateMarkdownLint(fixturePath)) ?? []
+        const errorsDetails = lintResults.map((result) => {
+          assert.deepEqual(result.ruleNames, relativeLinksRule.names)
+          assert.deepEqual(
+            result.ruleDescription,
+            relativeLinksRule.description,
+          )
+          return result.errorDetail
+        })
+        assert.deepStrictEqual(
+          errorsDetails,
+          errors,
+          `${fixturePath}: Expected errors`,
+        )
+      })
+    }
   })
 
-  await t.test("should be invalid", async (t) => {
-    await t.test("with a non-existing heading fragment", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/invalid/non-existing-heading-fragment/non-existing-heading-fragment.md",
-      )
-      assert.equal(lintResults?.length, 1)
-      assert.deepEqual(lintResults?.[0]?.ruleNames, relativeLinksRule.names)
-      assert.equal(
-        lintResults?.[0]?.ruleDescription,
-        relativeLinksRule.description,
-      )
-      assert.equal(
-        lintResults?.[0]?.errorDetail,
-        '"./awesome.md#non-existing-heading" should have a valid fragment identifier',
-      )
-    })
+  await t.test("should be valid", async (t) => {
+    const testCases = [
+      {
+        name: "should be valid with an existing anchor name fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-anchor-name-fragment/existing-anchor-name-fragment.md",
+      },
+      {
+        name: "should be valid with an existing element id fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-element-id-fragment/existing-element-id-fragment.md",
+      },
+      {
+        name: "should be valid with an existing heading fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-heading-fragment/existing-heading-fragment.md",
+      },
+      {
+        name: 'should be valid with an existing heading fragment with accents (e.g: "é")',
+        fixturePath:
+          "test/fixtures/valid/existing-heading-with-accents/existing-heading-with-accents.md",
+      },
+      {
+        name: "should only parse markdown files for fragments checking",
+        fixturePath:
+          "test/fixtures/valid/only-parse-markdown-files-for-fragments/only-parse-markdown-files-for-fragments.md",
+      },
+      {
+        name: "should support lines and columns range numbers in link fragments",
+        fixturePath:
+          "test/fixtures/valid/valid-line-column-range-number-fragment/valid-line-column-range-number-fragment.md",
+      },
+      {
+        name: 'should be valid with valid heading "like" line number fragment',
+        fixturePath:
+          "test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md",
+      },
+      {
+        name: "should be valid with valid line number fragment",
+        fixturePath:
+          "test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md",
+      },
+      {
+        name: "should be valid with an existing file",
+        fixturePath: "test/fixtures/valid/existing-file.md",
+      },
+      {
+        name: "should be valid with an existing image",
+        fixturePath: "test/fixtures/valid/existing-image.md",
+      },
+      {
+        name: "should ignore absolute paths",
+        fixturePath: "test/fixtures/valid/ignore-absolute-paths.md",
+      },
+      {
+        name: "should ignore external links",
+        fixturePath: "test/fixtures/valid/ignore-external-links.md",
+      },
+      {
+        name: "should ignore checking fragment in own file",
+        fixturePath:
+          "test/fixtures/valid/ignore-fragment-checking-in-own-file.md",
+      },
+    ]
 
-    await t.test("with a non-existing file", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/invalid/non-existing-file.md",
-      )
-      assert.equal(lintResults?.length, 1)
-      assert.deepEqual(lintResults?.[0]?.ruleNames, relativeLinksRule.names)
-      assert.equal(
-        lintResults?.[0]?.ruleDescription,
-        relativeLinksRule.description,
-      )
-      assert.equal(
-        lintResults?.[0]?.errorDetail,
-        '"./index.test.js" should exist in the file system',
-      )
-    })
-
-    await t.test("with a non-existing image", async () => {
-      const lintResults = await validateMarkdownLint(
-        "test/fixtures/invalid/non-existing-image.md",
-      )
-      assert.equal(lintResults?.length, 1)
-      assert.deepEqual(lintResults?.[0]?.ruleNames, relativeLinksRule.names)
-      assert.equal(
-        lintResults?.[0]?.ruleDescription,
-        relativeLinksRule.description,
-      )
-      assert.equal(
-        lintResults?.[0]?.errorDetail,
-        '"./image.png" should exist in the file system',
-      )
-    })
+    for (const { name, fixturePath } of testCases) {
+      await t.test(name, async () => {
+        const lintResults = (await validateMarkdownLint(fixturePath)) ?? []
+        const errorsDetails = lintResults.map((result) => {
+          return result.errorDetail
+        })
+        assert.equal(
+          errorsDetails.length,
+          0,
+          `${fixturePath}: Expected no errors, got ${errorsDetails.join(", ")}`,
+        )
+      })
+    }
   })
 })

test/utils.test.js

@@ -1,10 +1,14 @@
-const { test } = require("node:test")
-const assert = require("node:assert/strict")
+import { test } from "node:test"
+import assert from "node:assert/strict"
 
-const {
+import {
   convertHeadingToHTMLFragment,
   getMarkdownHeadings,
-} = require("../src/utils.js")
+  getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
+} from "../src/utils.js"
 
 test("utils", async (t) => {
   await t.test("convertHeadingToHTMLFragment", async () => {
@@ -34,4 +38,42 @@ test("utils", async (t) => {
       ["Hello", "World", "Hello, world!"],
     )
   })
+
+  await t.test("getMarkdownIdOrAnchorNameFragments", async () => {
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments(
+        '<a name="anchorName" id="anchorId">Link</a>',
+      ),
+      ["#anchorId"],
+    )
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments('<a name="anchorName">Link</a>'),
+      ["#anchorName"],
+    )
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments("<a>Link</a>"),
+      [],
+    )
+    assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a>"), [])
+    assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a id=>"), [])
+  })
+
+  await t.test("isValidIntegerString", async () => {
+    assert.strictEqual(isValidIntegerString("1"), true)
+    assert.strictEqual(isValidIntegerString("45"), true)
+    assert.strictEqual(isValidIntegerString("1abc"), false)
+    assert.strictEqual(isValidIntegerString("1.0"), false)
+  })
+
+  await t.test("getNumberOfLines", async () => {
+    assert.strictEqual(getNumberOfLines(""), 1)
+    assert.strictEqual(getNumberOfLines("Hello"), 1)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld"), 2)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n"), 3)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n\n"), 4)
+  })
+
+  await t.test("getLineNumberStringFromFragment", async () => {
+    assert.strictEqual(getLineNumberStringFromFragment("#L50"), "50")
+  })
 })

tsconfig.json

@@ -2,13 +2,14 @@
   "compilerOptions": {
     "lib": ["ESNext"],
     "target": "ESNext",
-    "module": "CommonJS",
-    "moduleResolution": "Node",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
     "checkJs": true,
     "allowJs": true,
     "noEmit": true,
     "rootDir": ".",
     "baseUrl": ".",
+    "skipLibCheck": true,
     "strict": true,
     "allowUnusedLabels": false,
     "allowUnreachableCode": false,