I'm looking to implement something similar to this in an AngularJS directive:

https://github.com/geniuscarrier/scrollToTop/blob/master/jquery.scrollToTop.js

It's fairly straightforward, when you are not at the top of the page it will fade in a button to scroll to the top:

$(window).scroll(function() {

  if ($(this).scrollTop() > 100) {

    $this.fadeIn();

  } else {

    $this.fadeOut();

  }

});

However I'm having a hard time finding how to get the current scroll location in Angular. I'd rather not have to use jQuery just for this single thing.