Besides JS, it offers good CSS and HTML editors as well. Nice bonus considering the usual nature of JS development. Notably the CSS editor provides nice preview functionality.
Netbeans provides native support for Mercurial. The integration is seamless. Git and co. are available as plugins.
If you happen to like vim, there's a nice plugin available that you might find interesting. With jVi you just might get the best of the both worlds. :)