While Markdown allows various HTML tags to be used, this article is about how to use footnotes and notes. We’ll use the Node.js package library markdown-it-footnote to enable footnotes and notes in Markdown.
Let’s add footnotes and notes to Markdown with markdown-it-footnote.
npm install markdown-it-footnote --save

var md = require('markdown-it')()
.use(require('markdown-it-footnote'));
console.log( md.render( "Here is a footnote reference,[^1] and another.[^longnote]\n\n[^1]: Here is the footnote." ) );
</html>
<p>Here is a footnote reference,<sup class="footnote-ref">[[1]](#fn1)</sup> and another.[^longnote]</p>
<hr class="footnotes-sep">
<section class="footnotes">
<ol class="footnotes-list">
<li id="fn1" class="footnote-item"><p>Here is the footnote. [↩︎](#fnref1)</p>
</li>
</ol>
</section>
