Grab it with Bower: bower install ng-ScrollSpy.js

Include it in your AngularJS application

var myApp = angular.module( 'myApp', [ 'ngScrollSpy' ] );

The following line is your navigation item element which will be given an active class when the specified ID is spied upon. It is element type unspecific.

<span data-scrollspy-listen="myID">myID</span>

This is the element you wish to spy on.

<section id="myID" data-scrollspy-broadcast></section>

NOTE: this AngularJS module is simply a scrollspy, anchor linking / smooth scrolling is another modules concern.