Notes

• An arbitrary string ("savestate") is passed in as the last argument of function initListGroup() inside this page, "sample.html", enabling the session-only cookie persistent feature. What this means is that the script will save and load the last state of the chained Selection lists when you reload or return to this page. See the documentation in chainedmenu.html for more info.
• Disable empty lists feature is enabled, so empty lists are disabled (grayed out).

Dynamic Drive- Chained Select Menu