Render html in heading

src/Slugger.js

@@ -13,6 +13,9 @@ module.exports = class Slugger {
     let slug = value
       .toLowerCase()
       .trim()
+      // remove html tags
+      .replace(/<[!\/a-z].*?>/ig, '')
+      // remove unwanted chars
       .replace(/[\u2000-\u206F\u2E00-\u2E7F\\'!"#$%&()*+,./:;<=>?@[\]^`{|}~]/g, '')
       .replace(/\s/g, '-');
 

src/TextRenderer.js

@@ -20,6 +20,10 @@ module.exports = class TextRenderer {
     return text;
   }
 
+  html(text) {
+    return text;
+  }
+
   text(text) {
     return text;
   }

test/specs/new/headings_id.html

@@ -1,3 +1,5 @@
+<h3 id="heading-with-html">Heading with <em>html</em></h3>
+
 <h3 id="heading-with-a-link">Heading with a <a href="http://github.com/">link</a></h3>
 
 <h3 id="heading-with-some-italic-text">Heading with some <em>italic text</em></h3>
@@ -10,4 +12,4 @@ <h3 id="or-even-code">Or even <code>code</code></h3>
 
 <h3 id="what-about-strikethrough">What about <del>strikethrough</del></h3>
 
-<h2 id="and-a-ref-link">And a ref <a href="/some/url" title="link to nowhere">link</a></h2>
+<h2 id="and-a-ref-link">And a ref <a href="/some/url" title="link to nowhere">link</a></h2>

test/specs/new/headings_id.md

@@ -1,3 +1,5 @@
+### Heading with <em>html</em>
+
 ### Heading with a [link](http://github.com/)
 
 ### Heading with some _italic text_
@@ -11,4 +13,4 @@
 
 ## And a ref [link][destination]
 
-[destination]: /some/url "link to nowhere"
+[destination]: /some/url "link to nowhere"