title: Cross-Browser Method to Determine Vertical Scroll Percentage in Javascript
body: <p>How can I find out what percentage of the vertical scrollbar a user has moved through at any given point?</p>
  
  <p>It's easy enough to trap the <code>onscroll</code> event to fire when the user scrolls down the page, but how do I find out within that event how far they have scrolled?  In this case, the percentage particularly is what's important.  I'm not particularly worried about a solution for IE6.</p>
  
  <p>Do any of the major frameworks (Dojo, jQuery, Prototype, Mootools) expose this in a simple cross-browser compatible way?</p>