fix: chapter number increases as the number of marked.parse calls

src/index.ts

@@ -46,6 +46,16 @@ export default function markedTableOfContentsExtension(
     }
   };
 
+  function renderToc() {
+    if (headings) {
+      tocCache = renderTableOfContent(headings, className) + '\n';
+      // clear headings for next run, to prevent headings cumulating and memory leak
+      headings = null;
+      fixHeadingDepth = null;
+      numberingHeading = null;
+    }
+  }
+
   const tableOfContentsExtension = {
     name: 'toc',
     level: 'block' as const,
@@ -63,19 +73,16 @@ export default function markedTableOfContentsExtension(
       }
     },
     renderer() {
-      if (headings) {
-        tocCache = renderTableOfContent(headings, className) + '\n';
-        // clear headings for next run, to prevent headings cumulating and memory leak
-        headings = null;
-        fixHeadingDepth = null;
-        numberingHeading = null;
-      }
+      renderToc();
       return tocCache;
     }
   };
 
   const rendererHeadingWithChapterNumber = {
     heading(this: Renderer, text: string, level: number, raw: string, slugger: Slugger) {
+      // fixme: this is to ensure clean of 'headings' when `[toc]' not present in markdown input
+      renderToc();
+
       const chapterNumber = chapterNumbers.shift();
 
       const id = this.options.headerIds

src/test/toc.test.ts

@@ -90,4 +90,37 @@ describe('marked-toc-extension', () => {
 
     expect(marked.parse(md)).toEqual(expectedHtml);
   });
+
+  test('should generate chapter number without toc', () => {
+    const md = removeLeadingSpaces(`
+      ## l2
+      ### l3
+      # l1
+      `);
+
+    const expectedHtml = removeLeadingSpaces(`
+      <h1 id="l2">1 l2</h1>
+      <h2 id="l3">1.1 l3</h2>
+      <h1 id="l1">2 l1</h1>
+      `);
+
+    expect(marked.parse(md)).toEqual(expectedHtml);
+  });
+
+  test('should generate the same chapter number without toc when call multiple times', () => {
+    const md = removeLeadingSpaces(`
+      ## l2
+      ### l3
+      # l1
+      `);
+
+    const expectedHtml = removeLeadingSpaces(`
+      <h1 id="l2">1 l2</h1>
+      <h2 id="l3">1.1 l3</h2>
+      <h1 id="l1">2 l1</h1>
+      `);
+
+    expect(marked.parse(md)).toEqual(expectedHtml);
+    expect(marked.parse(md)).toEqual(expectedHtml);
+  });
 });