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/md022.mjs

@@ -0,0 +1,97 @@
+// @ts-check
+
+import { addErrorDetailIf, isBlankLine } from "../helpers/helpers.cjs";
+import { getBlockQuotePrefixText, getHeadingLevel } from "../helpers/micromark-helpers.cjs";
+import { filterByTypesCached } from "./cache.mjs";
+
+const defaultLines = 1;
+
+const getLinesFunction = (linesParam) => {
+  if (Array.isArray(linesParam)) {
+    const linesArray = new Array(6).fill(defaultLines);
+    for (const [ index, value ] of [ ...linesParam.entries() ].slice(0, 6)) {
+      linesArray[index] = value;
+    }
+    return (heading) => linesArray[getHeadingLevel(heading) - 1];
+  }
+  // Coerce linesParam to a number
+  const lines = (linesParam === undefined) ? defaultLines : Number(linesParam);
+  return () => lines;
+};
+
+/** @type {import("./markdownlint.mjs").Rule} */
+export default {
+  "names": [ "MD022", "blanks-around-headings" ],
+  "description": "Headings should be surrounded by blank lines",
+  "tags": [ "headings", "blank_lines" ],
+  "parser": "micromark",
+  "function": function MD022(params, onError) {
+    const getLinesAbove = getLinesFunction(params.config.lines_above);
+    const getLinesBelow = getLinesFunction(params.config.lines_below);
+    const { lines } = params;
+    const blockQuotePrefixes = filterByTypesCached([ "blockQuotePrefix", "linePrefix" ]);
+    for (const heading of filterByTypesCached([ "atxHeading", "setextHeading" ])) {
+      const { startLine, endLine } = heading;
+      const line = lines[startLine - 1].trim();
+
+      // Check lines above
+      const linesAbove = getLinesAbove(heading);
+      if (linesAbove >= 0) {
+        let actualAbove = 0;
+        for (
+          let i = 0;
+          (i < linesAbove) && isBlankLine(lines[startLine - 2 - i]);
+          i++
+        ) {
+          actualAbove++;
+        }
+        addErrorDetailIf(
+          onError,
+          startLine,
+          linesAbove,
+          actualAbove,
+          "Above",
+          line,
+          undefined,
+          {
+            "insertText": getBlockQuotePrefixText(
+              blockQuotePrefixes,
+              startLine - 1,
+              linesAbove - actualAbove
+            )
+          }
+        );
+      }
+
+      // Check lines below
+      const linesBelow = getLinesBelow(heading);
+      if (linesBelow >= 0) {
+        let actualBelow = 0;
+        for (
+          let i = 0;
+          (i < linesBelow) && isBlankLine(lines[endLine + i]);
+          i++
+        ) {
+          actualBelow++;
+        }
+        addErrorDetailIf(
+          onError,
+          startLine,
+          linesBelow,
+          actualBelow,
+          "Below",
+          line,
+          undefined,
+          {
+            "lineNumber": endLine + 1,
+            "insertText": getBlockQuotePrefixText(
+              blockQuotePrefixes,
+              endLine + 1,
+              linesBelow - actualBelow
+            )
+          }
+        );
+      }
+    }
+  }
+};