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/md056.mjs

@@ -0,0 +1,50 @@
+// @ts-check
+
+import { addErrorDetailIf } from "../helpers/helpers.cjs";
+import { getParentOfType } from "../helpers/micromark-helpers.cjs";
+import { filterByTypesCached } from "./cache.mjs";
+
+const makeRange = (start, end) => [ start, end - start + 1 ];
+
+/** @typedef {import("micromark-extension-gfm-table")} */
+
+/** @type {import("./markdownlint.mjs").Rule} */
+export default {
+  "names": [ "MD056", "table-column-count" ],
+  "description": "Table column count",
+  "tags": [ "table" ],
+  "parser": "micromark",
+  "function": function MD056(params, onError) {
+    const rows = filterByTypesCached([ "tableDelimiterRow", "tableRow" ]);
+    let expectedCount = 0;
+    let currentTable = null;
+    for (const row of rows) {
+      const table = getParentOfType(row, [ "table" ]);
+      if (currentTable !== table) {
+        expectedCount = 0;
+        currentTable = table;
+      }
+      const cells = row.children.filter((child) => [ "tableData", "tableDelimiter", "tableHeader" ].includes(child.type));
+      const actualCount = cells.length;
+      expectedCount ||= actualCount;
+      let detail = undefined;
+      let range = undefined;
+      if (actualCount < expectedCount) {
+        detail = "Too few cells, row will be missing data";
+        range = [ row.endColumn - 1, 1 ];
+      } else if (expectedCount < actualCount) {
+        detail = "Too many cells, extra data will be missing";
+        range = makeRange(cells[expectedCount].startColumn, row.endColumn - 1);
+      }
+      addErrorDetailIf(
+        onError,
+        row.endLine,
+        expectedCount,
+        actualCount,
+        detail,
+        undefined,
+        range
+      );
+    }
+  }
+};