Progress converting from CommonJS -> ESM

.eslintrc.json

@@ -0,0 +1,18 @@
+{
+  "root": true,
+  "parserOptions": {
+    "ecmaVersion": 2020
+  },
+  "env": {
+    "es6": true,
+    "node": true,
+    "jest": true
+  },
+  "plugins": ["github"],
+  "extends": ["plugin:github/recommended"],
+  "rules": {
+    "import/no-commonjs": "off",
+    "filenames/match-regex": "off",
+    "i18n-text/no-en": "off"
+  }
+}

.markdownlint-cli2.mjs

@@ -0,0 +1,12 @@
+// import init from "./index.js";
+
+const options = {
+  default: false,
+  "heading-increment": true,
+  "no-alt-text": true,
+  "single-h1": true,
+  "no-emphasis-as-heading": true,
+  "first-line-heading": true,
+};
+export const config = options;
+export const customRules = ["./index.js"];

.nvmrc

@@ -1 +1 @@
-14
+18

index.js

@@ -1,19 +1,18 @@
-const _ = require("lodash");
+import _ from "lodash-es";
 
-const accessibilityRules = require("./style/accessibility.json");
-const base = require("./style/base.json");
-const gitHubCustomRules = require("./src/rules/index").rules;
-
-module.exports = [...gitHubCustomRules];
+import * as accessibilityRules from "./style/accessibility.json";
+import * as base from "./style/base.json";
+import { githubMarkdownLint } from "./src/rules/index.js";
 
 const offByDefault = ["no-empty-alt-text"];
+const foo = base;
 
-for (const rule of gitHubCustomRules) {
-  const ruleName = rule.names[1];
-  base[ruleName] = offByDefault.includes(ruleName) ? false : true;
-}
+// for (const rule of githubMarkdownLint) {
+//   const ruleName = rule.names[1];
+//   foo[ruleName] = offByDefault.includes(ruleName) ? false : true;
+// }
 
-module.exports.init = function init(consumerConfig) {
+export function init(consumerConfig) {
   // left overwrites right
   return _.defaultsDeep(consumerConfig, accessibilityRules, base);
-};
+}

jest.config.json

@@ -0,0 +1,4 @@
+{
+  "transform": {
+  }
+}

package.json

@@ -1,26 +1,30 @@
 {
   "name": "@github/markdownlint-github",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "An opinionated collection of markdownlint rules used by GitHub.",
-  "main": "index.js",
+  "type": "module",
+  "exports": "./index.js",
+  "engines": {
+    "node": ">=18"
+  },
   "directories": {
     "test": "test"
   },
   "scripts": {
     "publish": "npm publish --access public --@github:registry=https://registry.npmjs.org",
-    "test": "npm run lint && jest",
+    "test": "NODE_OPTIONS=--experimental-vm-modules jest",
     "lint": "markdownlint-cli2 \"**/*.{md,mdx}\" \"!node_modules\" \"!docs/rules\" \"!test/example.md\" && eslint .",
     "lint:fix": "npm run lint -- --fix"
   },
   "dependencies": {
-    "lodash": "^4.17.15"
+    "lodash-es": "^4.17.15"
   },
   "devDependencies": {
     "eslint": "^8.22.0",
     "eslint-plugin-github": "^5.0.1",
     "jest": "^29.5.0",
     "markdownlint": "^0.37.3",
-    "markdownlint-cli2": "^0.16.0"
+    "markdownlint-cli2": "^0.17.0"
   },
   "repository": {
     "type": "git",

src/helpers/strip-and-downcase-text.js

@@ -1,10 +1,8 @@
 /* Downcase and strip extra whitespaces and punctuation */
-function stripAndDowncaseText(text) {
+export function stripAndDowncaseText(text) {
   return text
     .toLowerCase()
     .replace(/[.,/#!$%^&*;:{}=\-_`~()]/g, "")
     .replace(/\s+/g, " ")
     .trim();
 }
-
-module.exports = { stripAndDowncaseText };

src/rules/index.js

@@ -1,7 +1,9 @@
-module.exports = {
-  rules: [
-    require("./no-default-alt-text"),
-    require("./no-generic-link-text"),
-    require("./no-empty-alt-text"),
-  ],
-};
+import { noEmptyStringAltRule } from "./no-empty-alt-text.js";
+import { noGenericLinkTextRule } from "./no-generic-link-text.js";
+import { altTextRule } from "./no-default-alt-text.js";
+
+export const githubMarkdownLint = [
+  altTextRule,
+  noGenericLinkTextRule,
+  noEmptyStringAltRule,
+];

src/rules/no-default-alt-text.js

@@ -14,11 +14,11 @@ const combinedRegex = `(${[defaultScreenshotRegex, imageRegex].join("|")})`;
 const markdownAltRegex = new RegExp(`!\\[${combinedRegex}\\]\\(.*\\)`, "gid");
 const htmlAltRegex = new RegExp(`alt=["']${combinedRegex}["']`, "gid");
 
-module.exports = {
+export const altTextRule = {
   names: ["GH001", "no-default-alt-text"],
   description: "Images should have meaningful alternative text (alt text)",
   information: new URL(
-    "https://github.com/github/markdownlint-github/blob/main/docs/rules/GH001-no-default-alt-text.md",
+    "https://github.com/github/markdownlint-github/blob/main/docs/rules/GH001-no-default-alt-text.md"
   ),
   tags: ["accessibility", "images"],
   function: function GH001(params, onError) {
@@ -30,12 +30,12 @@ module.exports = {
             token.content.includes("<img") &&
             token.children.some((child) => child.type === "html_inline"))
         );
-      },
+      }
     );
     const inlineImages = params.parsers.markdownit.tokens.filter(
       (token) =>
         token.type === "inline" &&
-        token.children.some((child) => child.type === "image"),
+        token.children.some((child) => child.type === "image")
     );
 
     for (const token of [...htmlTagsWithImages, ...inlineImages]) {

src/rules/no-empty-alt-text.js

@@ -1,8 +1,8 @@
-module.exports = {
+export const noEmptyStringAltRule = {
   names: ["GH003", "no-empty-alt-text"],
   description: "Please provide an alternative text for the image.",
   information: new URL(
-    "https://github.com/github/markdownlint-github/blob/main/docs/rules/GH003-no-empty-alt-text.md",
+    "https://github.com/github/markdownlint-github/blob/main/docs/rules/GH003-no-empty-alt-text.md"
   ),
   tags: ["accessibility", "images"],
   function: function GH003(params, onError) {
@@ -14,7 +14,7 @@ module.exports = {
             token.content.includes("<img") &&
             token.children.some((child) => child.type === "html_inline"))
         );
-      },
+      }
     );
 
     const ImageRegex = new RegExp(/<img(.*?)>/, "gid");