I have no idea of AJAX and here, the code is very bad in design. Not html is
JSP but
Java code. Its like all field details are in Map, and this Map is passed onto some class, which then parses the values and does out.println("..."); for writing the code. So I have to be very careful here, as I do not want to break the existing design. To change the values I have written onChange() already in the parsing Java class, and its working also. The main issue is that when A is disabled, B and C should not show anything and should be disabled, and pass NULL to underlying commands to be saved onto DB, but when A is enabled, then proper options are displayed in B and C drop-downs, and no blank space is shown.