Creating JavaScript drop down menu

A drop down menu is one in which menu items are normally kept hidden; only their parent nodes are visible to the viewers. When viewer clicks on a node, the node expanded vertically and the items under that node becomes visible. Here we shall discus how to develop a drop down menu for a web page with the help of JavaScript.
  
A CSS vertical menu
Below we take an example vertical menu which has three parent nodes- web hosting, web design and domain name. Under those parent nodes there are few children items. The HTML code of such a list is as follows.  more...