title: How to detect if user has reached almost the end of the page using jQuery?
body: <p>Right now I fire an event when the user has reached the bottom of the page using this:</p>
  
  <pre><code>$(window).scroll(function() {       
      if($(window).scrollTop() == $(document).height() - $(window).height()) {
          // do something
      }
  });
  </code></pre>
  
  <p>How can this be modified to fire the event when the user reached almost the end of the page, let's say 300px left?</p>