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.

lib/md048.mjs

@@ -0,0 +1,47 @@
+// @ts-check
+
+import { addErrorDetailIf } from "../helpers/helpers.cjs";
+import { getDescendantsByType } from "../helpers/micromark-helpers.cjs";
+import { filterByTypesCached } from "./cache.mjs";
+
+/**
+ * Return the string representation of a fence markup character.
+ *
+ * @param {string} markup Fence string.
+ * @returns {"tilde" | "backtick"} String representation.
+ */
+function fencedCodeBlockStyleFor(markup) {
+  switch (markup[0]) {
+    case "~":
+      return "tilde";
+    default:
+      return "backtick";
+  }
+};
+
+/** @type {import("./markdownlint.mjs").Rule} */
+export default {
+  "names": [ "MD048", "code-fence-style" ],
+  "description": "Code fence style",
+  "tags": [ "code" ],
+  "parser": "micromark",
+  "function": function MD048(params, onError) {
+    const style = String(params.config.style || "consistent");
+    let expectedStyle = style;
+    const codeFenceds = filterByTypesCached([ "codeFenced" ]);
+    for (const codeFenced of codeFenceds) {
+      const codeFencedFenceSequence =
+        getDescendantsByType(codeFenced, [ "codeFencedFence", "codeFencedFenceSequence" ])[0];
+      const { startLine, text } = codeFencedFenceSequence;
+      if (expectedStyle === "consistent") {
+        expectedStyle = fencedCodeBlockStyleFor(text);
+      }
+      addErrorDetailIf(
+        onError,
+        startLine,
+        expectedStyle,
+        fencedCodeBlockStyleFor(text)
+      );
+    }
+  }
+};