How do I use Bootstrap scrollspy?
AFAIK your bootstrap theme will be having bootstrap.js or bootstrap.min.js included. Generally, scrollspy plugin related code will be inside these files.

So try to recheck whether you have added nav-scrollspy to your div element. I think you might need to have 'id' for your div element and a proper link to it. 




&lt;!-- The navbar - The &lt;a&gt; elements are used to jump to a section in the scrollable area --&gt;
&lt;nav class="navbar navbar-inverse navbar-fixed-top"&gt;
  &lt;ul class="nav navbar-nav"&gt;
    &lt;li&gt;&lt;a href="#section1"&gt;Section 1&lt;/a&gt;&lt;/li&gt;
&lt;/nav&gt;

&lt;!-- Section 1 --&gt;
&lt;div id="section1"&gt;
  &lt;h1&gt;Section 1&lt;/h1&gt;
  &lt;p&gt;Try to scroll this page and look at the navigation bar while scrolling!&lt;/p&gt;
&lt;/div&gt;
&lt;/body&gt;


Also in Drupal 8, caching is a bit aggressive so try to rebuild your cache and check again. For better understanding refer http://www.sitepoint.com/understanding-bootstraps-affix-scrollspy-plugins/