feat(toc_obj): Support unnumbered headings (hexojs#269)

* feat(toc_obj): Support unnumbered headings

* Update readme

* Rollback TOC

* Fix typo

* Fix lint

Author: Cerallin

README.md

@@ -544,7 +544,7 @@ wordWrap('Once upon a time', {width: 1})
 
 ### tocObj(str, [options])
 
-Generate a table of contents in JSON format based on the given html string.
+Generate a table of contents in JSON format based on the given html string. Headings with attribute `data-toc-unnumbered="true"` will be marked as unnumbered.
 
 Option | Description | Default
 --- | --- | ---
@@ -601,6 +601,13 @@ tocObj(html, { max_depth: 2 });
   { text: 'Title 2.1', id: 'title_2_1', level: 2 },
 ]
 */
+
+tocObj('<h1 id="reference" data-toc-unnumbered="true">Reference</h1>')
+/*
+[
+  { text: 'Reference', id: 'reference', level: 1, unnumbered: true }
+]
+*/
 ```
 
 ### truncate(str, [options])

lib/toc_obj.js

@@ -13,6 +13,13 @@ const getId = ({ attribs = {}, parent }) => {
   return attribs.id || (!parent ? '' : getId(parent));
 };
 
+/**
+ * Identify a heading that to be unnumbered or not.
+ */
+const isUnnumbered = ({ attribs = {} }) => {
+  return attribs['data-toc-unnumbered'] === 'true';
+};
+
 function tocObj(str, options = {}) {
   const { min_depth, max_depth } = Object.assign({
     min_depth: 1,
@@ -31,6 +38,7 @@ function tocObj(str, options = {}) {
     const el = headings[i];
     const level = +el.name[1];
     const id = getId(el);
+    const unnumbered = isUnnumbered(el);
     let text = '';
     for (const element of el.children) {
       const elText = DomUtils.getText(element);
@@ -43,7 +51,9 @@ function tocObj(str, options = {}) {
     }
     if (!text) text = escapeHTML(DomUtils.getText(el));
 
-    result.push({ text, id, level });
+    const res = { text, id, level };
+    if (unnumbered) res.unnumbered = true;
+    result.push(res);
   }
 
   return result;

test/toc_obj.spec.js

@@ -165,5 +165,19 @@ describe('tocObj', () => {
 
       result.forEach(str => str[0].text.should.eql('foobarbaz'));
     });
+
+    it('unnumbered headings', () => {
+      const input = [
+        '<h1 id="title_1" data-toc-unnumbered="true">Title 1</h1>',
+        '<h2 data-toc-unnumbered="false" id="title_2">Title 2</h2>'
+      ].join('');
+
+      const expected = [
+        { text: 'Title 1', id: 'title_1', level: 1, unnumbered: true },
+        { text: 'Title 2', id: 'title_2', level: 2 }
+      ];
+
+      tocObj(input).should.eql(expected);
+    });
   });
 });