javascript code for colapsible menu or hover menu

HI:

 Can any one send me Javascript code to Collapsible menu or dropdown menu.My task is i have 2 categories namely Car,Bike.Categorey Car has subcategory Benz,Sonata similarly the Bike has subcategorey Yamaha,Herohonda.while clicking the category Car the subcategories Benz,Sonata  has to open then when categorey Bike is clicked the subcategorey Yamaha,Herohonda has to be opened  at the same time already opened subcategory Benz,Sonata  should be closed.Objective is when clicking the categorey particular subcategorey should be opned .please treate this mail is very urgent and send me code.

 

Thanks