Use webpack to create a CommonJS module from micromark's ESM implementation, convert to using that.

.eslintrc.json

@@ -15,6 +15,8 @@
     "demo/markdownlint-browser.js",
     "demo/markdownlint-browser.min.js",
     "example/typescript/type-check.js",
+    "micromark/micromark.js",
+    "micromark/micromark.dev.js",
     "test-repos/"
   ],
   "overrides": [

lib/micromark.mjs

@@ -1,8 +1,12 @@
 // @ts-check
 
+/* eslint-disable n/no-unpublished-import */
+
 import assert from "node:assert/strict";
-// eslint-disable-next-line n/no-unpublished-import
-import { parse, postprocess, preprocess } from "../micromark/exports.mjs";
+// @ts-ignore
+import micromark from "../micromark/micromark.js";
+// @ts-ignore
+const { parse, postprocess, preprocess } = micromark;
 
 /**
  * Markdown token.

micromark/.npmignore

@@ -0,0 +1,3 @@
+exports.mjs
+micromark.dev.js
+webpack.config.js

micromark/package.json

@@ -2,7 +2,8 @@
   "name": "markdownlint-micromark",
   "version": "0.1.0",
   "description": "A trivial package that re-exports some micromark functionality as a CommonJS module",
-  "exports": "./exports.mjs",
+  "type": "commonjs",
+  "exports": "./micromark.js",
   "author": "David Anson (https://dlaa.me/)",
   "license": "MIT",
   "homepage": "https://github.com/DavidAnson/markdownlint",
@@ -11,10 +12,17 @@
     "url": "https://github.com/DavidAnson/markdownlint.git"
   },
   "bugs": "https://github.com/DavidAnson/markdownlint/issues",
+  "scripts": {
+    "build": "webpack --no-stats"
+  },
   "engines": {
     "node": ">=14.18.0"
   },
   "dependencies": {
     "micromark": "3.1.0"
+  },
+  "devDependencies": {
+    "webpack": "5.75.0",
+    "webpack-cli": "5.0.1"
   }
 }

micromark/webpack.config.js

@@ -0,0 +1,34 @@
+// @ts-check
+
+"use strict";
+
+const shared = {
+  "entry": "./exports.mjs",
+  "output": {
+    "library": {
+      "type": "commonjs"
+    },
+    "path": __dirname
+  },
+  "target": "node"
+};
+
+module.exports = [
+  {
+    ...shared,
+    "mode": "production",
+    "output": {
+      ...shared.output,
+      "filename": "micromark.js"
+    }
+  },
+  {
+    ...shared,
+    "devtool": false,
+    "mode": "development",
+    "output": {
+      ...shared.output,
+      "filename": "micromark.dev.js"
+    }
+  }
+];

package.json

@@ -29,7 +29,8 @@
     "build-demo": "node scripts copy node_modules/markdown-it/dist/markdown-it.min.js demo/markdown-it.min.js && cd demo && webpack --no-stats",
     "build-docs": "node doc-build/build-rules.mjs",
     "build-example": "npm install --no-save --ignore-scripts grunt grunt-cli gulp through2",
-    "ci": "npm-run-all --continue-on-error --parallel lint serial-config-docs serial-declaration-demo test-cover && git diff --exit-code",
+    "build-micromark": "cd micromark && npm run build",
+    "ci": "npm run build-micromark && npm-run-all --continue-on-error --parallel lint serial-config-docs serial-declaration-demo test-cover && git diff --exit-code",
     "clone-test-repos-apache-airflow": "cd test-repos && git clone https://github.com/apache/airflow apache-airflow --depth 1 --no-tags --quiet",
     "clone-test-repos-dotnet-docs": "cd test-repos && git clone https://github.com/dotnet/docs dotnet-docs --depth 1 --no-tags --quiet",
     "clone-test-repos-electron-electron": "cd test-repos && git clone https://github.com/electron/electron electron-electron --depth 1 --no-tags --quiet",
@@ -52,7 +53,7 @@
     "serial-config-docs": "npm run build-config && npm run build-docs",
     "serial-declaration-demo": "npm run build-declaration && npm-run-all --continue-on-error --parallel build-demo test-declaration",
     "test": "ava test/markdownlint-test.js test/markdownlint-test-config.js test/markdownlint-test-custom-rules.js test/markdownlint-test-helpers.js test/markdownlint-test-micromark.mjs test/markdownlint-test-result-object.js test/markdownlint-test-scenarios.js",
-    "test-cover": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 npm test",
+    "test-cover": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --exclude 'test/**' --exclude 'micromark/**' npm test",
     "test-declaration": "cd example/typescript && tsc && node type-check.js",
     "test-extra": "ava --timeout=5m test/markdownlint-test-extra-parse.js test/markdownlint-test-extra-type.js",
     "update-snapshots": "ava --update-snapshots test/markdownlint-test-micromark.mjs test/markdownlint-test-scenarios.js",