JSFiddle - React, Tailwind, and code Playground

HTML

## Titulo

JavaScript

var str = document.body.innerHTML;
var parsed = (function (markdown) {
    var parts = markdown.match(/(#*)\s?(\w+)/);
    if (!parts) return '';
    var heading = parts[1].length + 1;
    var text = parts[2];
    return ['<h', heading, '>', text, '</', heading, '>'].join('');
})(str);

document.body.innerHTML = parsed;