Convert markdownlint library to an ECMAScript module, replace markdownlint-micromark with micromark, stop publishing (large) markdownlint-browser.js, see https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c for guidance.

test/esm-helpers.mjs

@@ -0,0 +1,38 @@
+// @ts-check
+
+import fs from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+/**
+ * Gets the file name of the current module.
+ * Shims import.meta.filename for Node 18.
+ *
+ * @param {Object} meta ESM import.meta object.
+ * @returns {string} File name.
+ */
+// eslint-disable-next-line no-underscore-dangle
+export const __filename = (meta) => fileURLToPath(meta.url);
+
+/**
+ * Gets the directory name of the current module.
+ * Shims import.meta.dirname for Node 18.
+ *
+ * @param {Object} meta ESM import.meta object.
+ * @returns {string} Directory name.
+ */
+// eslint-disable-next-line no-underscore-dangle
+export const __dirname = (meta) => path.dirname(__filename(meta));
+
+/**
+ * Imports a file as JSON.
+ * Avoids "ExperimentalWarning: Importing JSON modules is an experimental feature and might change at any time".
+ *
+ * @param {Object} meta ESM import.meta object.
+ * @param {string} file JSON file to import.
+ * @returns {Promise<Object>} JSON object.
+ */
+export const importWithTypeJson = async(meta, file) => (
+  // @ts-ignore
+  JSON.parse(await fs.readFile(path.resolve(__dirname(meta), file)))
+);