title: Lazy-load external JavaScript in one of AngularJS controller
body: <p>Some of my routes needs functionality from external JS. I don't want to load them all at once since those JS are needed only in certain routes (e.g. <code>/upload</code> needs some JS for photo uploading, <code>/photos</code> needs another JS for lightbox, <code>/funny</code> needs JS for animation stuff, etc). </p>
  
  <p>What's the best practice for lazily loading those external JavaScripts?</p>
  
  <p>Those routes can be accessed multiple times (e.g. user can go to <code>/upload</code> then <code>/photos</code> then <code>/upload</code> again)</p>