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/md042.mjs

@@ -0,0 +1,56 @@
+// @ts-check
+
+import { addErrorContext } from "../helpers/helpers.cjs";
+import { getDescendantsByType } from "../helpers/micromark-helpers.cjs";
+import { getReferenceLinkImageData, filterByTypesCached } from "./cache.mjs";
+
+/** @type {import("./markdownlint.mjs").Rule} */
+export default {
+  "names": [ "MD042", "no-empty-links" ],
+  "description": "No empty links",
+  "tags": [ "links" ],
+  "parser": "micromark",
+  "function": function MD042(params, onError) {
+    const { definitions } = getReferenceLinkImageData();
+    const isReferenceDefinitionHash = (token) => {
+      const definition = definitions.get(token.text.trim());
+      return (definition && (definition[1] === "#"));
+    };
+    const links = filterByTypesCached([ "link" ]);
+    for (const link of links) {
+      const labelText = getDescendantsByType(link, [ "label", "labelText" ]);
+      const reference = getDescendantsByType(link, [ "reference" ]);
+      const resource = getDescendantsByType(link, [ "resource" ]);
+      const referenceString = getDescendantsByType(reference, [ "referenceString" ]);
+      const resourceDestinationString = getDescendantsByType(resource, [ "resourceDestination", [ "resourceDestinationLiteral", "resourceDestinationRaw" ], "resourceDestinationString" ]);
+      const hasLabelText = labelText.length > 0;
+      const hasReference = reference.length > 0;
+      const hasResource = resource.length > 0;
+      const hasReferenceString = referenceString.length > 0;
+      const hasResourceDestinationString = resourceDestinationString.length > 0;
+      let error = false;
+      if (
+        hasLabelText &&
+        ((!hasReference && !hasResource) || (hasReference && !hasReferenceString))
+      ) {
+        error = isReferenceDefinitionHash(labelText[0]);
+      } else if (hasReferenceString && !hasResourceDestinationString) {
+        error = isReferenceDefinitionHash(referenceString[0]);
+      } else if (!hasReferenceString && hasResourceDestinationString) {
+        error = (resourceDestinationString[0].text.trim() === "#");
+      } else if (!hasReferenceString && !hasResourceDestinationString) {
+        error = true;
+      }
+      if (error) {
+        addErrorContext(
+          onError,
+          link.startLine,
+          link.text,
+          undefined,
+          undefined,
+          [ link.startColumn, link.endColumn - link.startColumn ]
+        );
+      }
+    }
+  }
+};