This is a basic directive allows you to scroll to the top of the document -- no more, no less. For advanced features, in my opinion, it should belong to a different directive. And to brag, there are already existing libraries that does more advanced feats such as angular-scroll.
Will be available in Bower on v1.0
bower install angular-to-top -S
Simply wrap your element with either one of the two:
<to-top> ... </to-top>
<div to-top> </div>
Additional options would be, speed and slide
<div to-top speed="1000"></div>
<div to-top slide="false"></div>