gistfile1.txt

$.support.positionFixed = (function () {
  var el, support,
      body = document.body || document.getElementsByTagName("body")[0] || document.documentElement;
  // Boolean indicating whether or not "position: fixed" is supported.

  // Using the DOM to create an element is much faster than using jQuery.
  el = document.createElement("div");
  el.style.position = "fixed";
  el.style.top = "10px";
  el.style.visibility = "hidden";

  // Use insertBefore instead of appendChild to circumvent an IE6 bug.
  // This arises when a base node is used.
  body.insertBefore(el, body.firstChild);
  support = parseInt(el.offsetTop, 10) - (body.scrollTop ? body.scrollTop : 0) === 10;
  body.removeChild(el);
  return support;
})();