title: Opposite of "scrollTop" in jQuery
body: <p>jQuery has a function called scrollTop which can be used to find the number of pixels hidden above the current page view.</p>
  
  <p>I'm not really sure why, but there is no scrollBottom function which returns the number of pixels below the current page view.</p>
  
  <p>Is there a jQuery plugin which adds this functionality? Or is it going to require some elaborate math with the window/document height and the scrollTop value?</p>