What is the simplest jQuery way to have a 'position:fixed' (always at top) div?

I'm relatively new to jQuery, but so far what I've seen I like. What I want is for a div (or any element) to be across the top of the page as if "position: fixed" worked in every browser.

I do not want something complicated. I do not want giant CSS hacks. I would prefer if just using jQuery (version 1.2.6) is good enough, but if I need jQuery-UI-core, then that's fine too.

I've tried $("#topBar").scrollFollow(); <-- but that goes slow... I want something to appear really fixed.

Using this HTML:

<div id="myElement" style="position: absolute">This stays at the top</div>

This is the javascript you want to use. It attaches an event to the window's scroll and moves the element down as far as you've scrolled.

$(window).scroll(function() {
    $('#myElement').css('top', $(this).scrollTop() + "px");
});

As pointed out in the comments below, it's not recommended to attach events to the scroll event - as the user scrolls, it fires A LOT, and can cause performance issues. Consider using it with Ben Alman's debounce/throttle plugin to reduce overhead.

For those browsers that do support "position: fixed" you can simply use javascript (jQuery) to change the position to "fixed" when scrolling. This eliminates the jumpiness when scrolling with the $(window).scroll(function()) solutions listed here.

Ben Nadel demonstrates this in his tutorial: Creating A Sometimes-Fixed-Position Element With jQuery