Sticky footer function

gistfile1.txt

var updateFooter = function ($footer) {
  var window_height = jQuery(window).height();
  var body_offset_top = jQuery('body').offset().top;
  var body_outer_height = jQuery('body').outerHeight();
  var body_height = jQuery('body').height();
  body_bottom = (body_offset_top + body_outer_height) - ((body_outer_height - body_height)/2);
  var footer_height = $footer.outerHeight(true);

  if (!$footer.hasClass('sticky') && window_height > body_bottom) {
    $footer.addClass('sticky');
  }
  else if ($footer.hasClass('sticky') && window_height < body_bottom + footer_height + 1) {
    $footer.removeClass('sticky');
  }
};