var headline = /^(\#{1,6})([^\#\n]+)$/m;
var links = /!?\[([^\]<>]+)\]\(([^ \)<>]+)( "[^\(\)\"]+")?\)/g;

while ((stra = headline.exec(str)) !== null) {
  count = stra[1].length;
  str = str.replace(stra[0], '<h' + count + '>' + stra[2] + '</h' + count + '>' + '\n');
}

while ((stra = links.exec(str)) !== null) {
  if (stra[0].substr(0, 1) === '!') {
    str = str.replace(stra[0], '<img src="' + stra[2] + '" alt="' + stra[1] + '" title="' + stra[1] + '" />\n');
  } else {
    str = str.replace(stra[0], '<a href="' + stra[2] + '">' + stra[1] + '</a>\n');
  }
}