"<div>...</div>BLBLBLBLB<p>...</p>BL<a>...</a><div>...</div>ffffff.jpg"
...Теперь у него две проблемы
var s = "<div>...</div>BLBLBLBLB<p>...</p>BL<a>...</a><div>...</div>ffffff.jpg";
var name = s.substring(s.lastIndexOf('>') + 1);
var s = "<div>...</div>BLBLBLBLB<p>...</p>BL<a>...</a><div>...</div>ffffff.jpg";
var name = /[^>]+$/.exec(s);