No, I do not use it in site development, for a few reasons.

First, the use of JS can enter some really funky usability problems into your site, particularly when dealing with JS for dynamic menus or onSelect type operations.

Second, US federal regulations require that all script functionality on my sites be available to persons with disabilities, surfing with assistive technology like screen readers for visually impaired people.

I'd rather just build a single, usable interface than have to deal with redundant systems. My servers can take the hits.