jQuery - get percentage scrolled from top/bottom

gistfile1.js

$.fn.percentScrolledTop = function() {
  var vals = [];
  this.each(function() {
    vals.push(+($(this).scrollTop() / this.scrollHeight));
  });
  return vals.length === 1 ? vals[0] : vals;
};

$.fn.percentScrolledBottom = function() {
  var vals = [];
  this.each(function() {
    var $this = $(this);
    vals.push(($this.scrollTop() + $this.height())  / this.scrollHeight);
  });
  return vals.length === 1 ? vals[0] : vals;
};