I think in the guy's original usage of the progress bars being able to dynamically update is not required. If you can provide the percentage through server-side code then javascript is not required.

If it needed to be a progress bar to show progress of something happening on the page, then javascript would be needed.

Well, there is CSS Animation. However, you could argue that it's not ready for use yet it lacks support in IE9 (IE10 has it) and Opera, plus older versions of other browsers.

(See: https://developer.mozilla.org/en/CSS/animation for further information)