function mark(str) {

  const lines = str.split`\n`;

  let wasLi;

  for (let i = 0; i < lines.length; i++) {

    const curr = lines[i];

    const line = curr.trim();

    const hdr = line.split`#`.length - 1;

    if (line === '') { 

      lines[i] = '<br>';

    } else if (hdr > 0) {

      lines[i] = `<h${hdr} style="margin-bottom:0">

        ${curr.replace(/#/g, '')}</h${hdr}>`;

    } else if (line === '***') {

      lines[i] = '<hr>';

    } else if (line.startsWith('- ')) {

      lines[i] = `${!wasLi ? '<ul>' : ''}

        <li>${curr.replace(/-\s+/, '')}</li>`;

      wasLi = true;

    } else if (wasLi) {

      lines[i - 1] += '</ul>\n';

      wasLi = false;

    }

  }

  return lines.join`\n`

    .replace(/\*\*(.+)\*\*/gm, '<b>$1</b>')

    .replace(/_(.+)_/gm, '<i>$1</i>')

    .replace(/~~(.+)~~/gm, '<strike>$1</strike>')

    .replace(/`(.+)`/gm, '<code>$1</code>');

}

// try it out

const md = document.body.appendChild(document.createElement('div'));

md.style.fontFamily = 'sans-serif';

md.innerHTML = `# Mini Markdown Subset

This is a subset of markdown stuff

## It includes

- headers

- **bold styles**

- _italic styles, <br> multiline fine..._

- \`code style\`

Other than ~~strikethrough~~ that is pretty much it... oh and **hr** tags

***

***

_here is some italic text with some bold text **nested** <br>within it etc..._

`;

md.innerHTML = mark(md.innerHTML);