master select list changes contents of slave select lists

[Dan Thomas]

I have one drop-down list (call it master) that needs to change the
contents of other drop down lists (slaves). Really, its changing which
item is "selected" or on top of the slave lists, but same idea.

Can this be done with Ruby and html? Would I need some sort of
on_change listener on the master? And then a way to change the
"selected" attribute on the slaves?

I am using Ruby and Sinatra.

Any help, or key words to look up, greatly appreciated. I have only a
few weeks experience on Ruby and HTML. Thanks.