Ask them how they ensure their pages continue to be usable when the user has JavaScript turned off or JavaScript isn't available.
There's no One True Answer, but you're fishing for an answer talking about some strategies for Progressive Enhancement.
Progressive Enhancement consists of
the following core principles:
- basic content should be accessible to all browsers
- basic functionality should be accessible to all browsers
- sparse, semantic markup contains all content
- enhanced layout is provided by externally linked CSS
- enhanced behavior is provided by [[Unobtrusive
JavaScript|unobtrusive]], externally
linked JavaScript
- end user browser preferences are respected
