fix: cleaner code + better error messages

.github/workflows/lint.yml

@@ -26,3 +26,4 @@ jobs:
       - run: "npm run lint:markdown"
       - run: "npm run lint:eslint"
       - run: "npm run lint:prettier"
+      - run: "npm run lint:javascript"

.husky/pre-commit

@@ -2,4 +2,5 @@
 . "$(dirname "$0")/_/husky.sh"
 
 npm run lint:staged
+npm run lint:javascript
 npm run test

README.md

@@ -43,7 +43,7 @@ With `awesome.md` content:
 Running [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2) with `markdownlint-rule-relative-links` will output:
 
 ```sh
-awesome.md:3 relative-links Relative links should be valid [Link "./invalid.txt" should exist in the file system]
+awesome.md:3 relative-links Relative links should be valid ["./invalid.txt" should exist in the file system]
 ```
 
 ### Additional features

jsconfig.json

@@ -0,0 +1,24 @@
+{
+  "compilerOptions": {
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "CommonJS",
+    "moduleResolution": "Node",
+    "checkJs": true,
+    "allowJs": true,
+    "noEmit": true,
+    "rootDir": ".",
+    "baseUrl": ".",
+    "strict": true,
+    "allowUnusedLabels": false,
+    "allowUnreachableCode": false,
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitAny": true,
+    "noImplicitOverride": true,
+    "noImplicitReturns": true,
+    "noUncheckedIndexedAccess": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "forceConsistentCasingInFileNames": true
+  }
+}

package.json

@@ -35,6 +35,7 @@
     "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 ./test",
     "release": "semantic-release",
@@ -48,6 +49,7 @@
   "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",
@@ -63,6 +65,7 @@
     "markdownlint-cli2": "0.11.0",
     "pinst": "3.0.0",
     "prettier": "3.1.1",
-    "semantic-release": "22.0.12"
+    "semantic-release": "22.0.12",
+    "typescript": "5.3.3"
   }
 }

src/index.js

@@ -5,22 +5,27 @@ const fs = require("node:fs")
 
 const {
   filterTokens,
-  addError,
   convertHeadingToHTMLFragment,
   getMarkdownHeadings,
 } = require("./utils.js")
 
+/** @typedef {import('markdownlint').Rule} MarkdownLintRule */
+
+/**
+ * @type {MarkdownLintRule}
+ */
 const customRule = {
   names: ["relative-links"],
   description: "Relative links should be valid",
   tags: ["links"],
   function: (params, onError) => {
     filterTokens(params, "inline", (token) => {
-      for (const child of token.children) {
-        const { lineNumber, type, attrs } = child
+      const children = token.children ?? []
+      for (const child of children) {
+        const { type, attrs, lineNumber } = child
 
-        /** @type {string | null} */
-        let hrefSrc = null
+        /** @type {string | undefined} */
+        let hrefSrc
 
         if (type === "link_open") {
           for (const attr of attrs) {
@@ -45,14 +50,13 @@ const customRule = {
           const isRelative =
             url.protocol === "file:" && !hrefSrc.startsWith("/")
           if (isRelative) {
-            const detail = `Link "${hrefSrc}"`
+            const detail = `"${hrefSrc}"`
 
             if (!fs.existsSync(url)) {
-              addError(
-                onError,
+              onError({
                 lineNumber,
-                `${detail} should exist in the file system`,
-              )
+                detail: `${detail} should exist in the file system`,
+              })
               continue
             }
 
@@ -74,11 +78,10 @@ const customRule = {
               })
 
               if (!headingsHTMLFragments.includes(url.hash)) {
-                addError(
-                  onError,
+                onError({
                   lineNumber,
-                  `${detail} should have a valid fragment`,
-                )
+                  detail: `${detail} should have a valid fragment identifier`,
+                })
               }
             }
           }

src/utils.js

@@ -1,11 +1,14 @@
 const MarkdownIt = require("markdown-it")
 
+/** @typedef {import('markdownlint').RuleParams} MarkdownLintRuleParams */
+/** @typedef {import('markdownlint').MarkdownItToken} MarkdownItToken */
+
 /**
  * Calls the provided function for each matching token.
  *
- * @param {object} params RuleParams instance.
+ * @param {MarkdownLintRuleParams} params RuleParams instance.
  * @param {string} type Token type identifier.
- * @param {Function} handler Callback function.
+ * @param {(token: MarkdownItToken) => void} handler Callback function.
  * @returns {void}
  */
 const filterTokens = (params, type, handler) => {
@@ -16,27 +19,6 @@ const filterTokens = (params, type, handler) => {
   }
 }
 
-/**
- * Adds a generic error object via the onError callback.
- *
- * @param {object} onError RuleOnError instance.
- * @param {number} lineNumber Line number.
- * @param {string} [detail] Error details.
- * @param {string} [context] Error context.
- * @param {number[]} [range] Column and length of error.
- * @param {object} [fixInfo] RuleOnErrorFixInfo instance.
- * @returns {void}
- */
-const addError = (onError, lineNumber, detail, context, range, fixInfo) => {
-  onError({
-    lineNumber,
-    detail,
-    context,
-    range,
-    fixInfo,
-  })
-}
-
 /**
  * Converts a Markdown heading into an HTML fragment according to the rules
  * used by GitHub.
@@ -98,8 +80,10 @@ const getMarkdownHeadings = (content) => {
       continue
     }
 
+    const children = token.children ?? []
+
     headings.push(
-      `${token.children
+      `${children
         .map((token) => {
           return token.content
         })
@@ -112,7 +96,6 @@ const getMarkdownHeadings = (content) => {
 
 module.exports = {
   filterTokens,
-  addError,
   convertHeadingToHTMLFragment,
   getMarkdownHeadings,
 }

test/basic.test.js

@@ -1,4 +1,4 @@
-const test = require("node:test")
+const { test } = require("node:test")
 const assert = require("node:assert/strict")
 
 const { markdownlint } = require("markdownlint").promises
@@ -14,33 +14,33 @@ test("ensure the rule validate correctly", async () => {
     },
     customRules: [relativeLinks],
   })
-  assert.equal(lintResults["test/fixtures/Valid.md"].length, 0)
-  assert.equal(lintResults["test/fixtures/Invalid.md"].length, 3)
+  assert.equal(lintResults["test/fixtures/Valid.md"]?.length, 0)
+  assert.equal(lintResults["test/fixtures/Invalid.md"]?.length, 3)
 
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][0]?.ruleDescription,
+    lintResults["test/fixtures/Invalid.md"]?.[0]?.ruleDescription,
     "Relative links should be valid",
   )
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][0]?.errorDetail,
-    'Link "./basic.test.js" should exist in the file system',
+    lintResults["test/fixtures/Invalid.md"]?.[0]?.errorDetail,
+    '"./basic.test.js" should exist in the file system',
   )
 
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][1]?.ruleDescription,
+    lintResults["test/fixtures/Invalid.md"]?.[1]?.ruleDescription,
     "Relative links should be valid",
   )
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][1]?.errorDetail,
-    'Link "../image.png" should exist in the file system',
+    lintResults["test/fixtures/Invalid.md"]?.[1]?.errorDetail,
+    '"../image.png" should exist in the file system',
   )
 
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][2]?.ruleDescription,
+    lintResults["test/fixtures/Invalid.md"]?.[2]?.ruleDescription,
     "Relative links should be valid",
   )
   assert.equal(
-    lintResults["test/fixtures/Invalid.md"][2]?.errorDetail,
-    'Link "./Valid.md#not-existing-heading" should have a valid fragment',
+    lintResults["test/fixtures/Invalid.md"]?.[2]?.errorDetail,
+    '"./Valid.md#not-existing-heading" should have a valid fragment identifier',
   )
 })

test/utils.test.js

@@ -1,4 +1,4 @@
-const test = require("node:test")
+const { test } = require("node:test")
 const assert = require("node:assert/strict")
 
 const {