fix(mdx-loader): Ignore contentTitle coming after Markdown thematicBreak (#9999)

packages/docusaurus-mdx-loader/src/remark/contentTitle/__tests__/index.test.ts

@@ -65,6 +65,21 @@ some **markdown** *content*
 
 # contentTitle 1
 
+some **markdown** *content*
+  `);
+
+      expect(result.data.contentTitle).toBeUndefined();
+    });
+
+    it('ignore contentTitle if after thematic break', async () => {
+      const result = await process(`
+
+Hey
+
+---
+
+# contentTitle 1
+
 some **markdown** *content*
   `);
 

packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts

@@ -34,7 +34,9 @@ const plugin: Plugin = function plugin(
     const {toString} = await import('mdast-util-to-string');
     const {visit, EXIT} = await import('unist-util-visit');
 
-    visit(root, 'heading', (headingNode: Heading, index, parent) => {
+    visit(root, ['heading', 'thematicBreak'], (node, index, parent) => {
+      if (node.type === 'heading') {
+        const headingNode = node as Heading;
         if (headingNode.depth === 1) {
           vfile.data.contentTitle = toString(headingNode);
           if (removeContentTitle) {
@@ -47,6 +49,11 @@ const plugin: Plugin = function plugin(
         if (headingNode.depth >= 1) {
           return EXIT;
         }
+      }
+      // We only handle contentTitle when it's above the first thematic break
+      if (node.type === 'thematicBreak') {
+        return EXIT;
+      }
       return undefined;
     });
   };