very-small-parser (Markdown demo)

HTML

<script type="module">
  import { markdown } from "//esm.sh/very-small-parser";

	const text = 'Hello __world__!';
  const ast = markdown.block.parse(text);
  
  document.body.innerHTML = `<pre><code>${JSON.stringify(ast, null, 2)}</code></pre>`;
</script>