metalsmith-headings-identifier/spec/fixture/src/scopedNonDuplicateIds.html

A Metalsmith plugin to add an id + anchor to all headings on a page

<h1>title A</h1>
<h2>subtitle</h2>
<h1>title B</h1>
<h2>subtitle</h2>
<h2>subtitle-1</h2>
<h2>subtitle-1</h2>