title: Debounce @HostListener event
body: <p>I'm implementing a simple infinite-scroll directive in Angular2.
  I'm using <code>@HostListener('window:scroll')</code> to get the scroll event and parsing the data from the <code>$target</code>.</p>
  
  <p>The question is, for every scroll event, everything will be checked once again with no need.</p>
  
  <p>I checked the ionic <code>infinite-scroll</code> directive for inspiration but they don't use <code>@HostListener</code>, they need a more granular control, I guess.</p>
  
  <p>I ended up on this issue while searching <a href="https://github.com/angular/angular/issues/13248" rel="noreferrer">https://github.com/angular/angular/issues/13248</a> but couldn't find any way to do what I want.</p>
  
  <p>I think if I create an Observable, subscribe to it with debounce and push (next) items to it, I will reach the behaviour I want, but I'm not being able to do that.</p>