Add Options to a Combo Box Using JavaScript

You can use a JavaScript function to modify the options available in a pull-down box on the page.

The following example adds a new blank selection at the top of the starthour field at Level 2 for new records:

function clearTimes()
 {
if (document.forms[0].startdate.value=="")
{
   try
   {
       document.forms[0].starthour.add(new Option("", "", true, true), document.forms[0].starthour.options[0]) //add blank option to beginning of starthour
       document.forms[0].startminute.add(new Option("", "", true, true), document.forms[0].startminute.options[0])
       document.forms[0].endhour.add(new Option("", "", true, true), document.forms[0].endhour.options[0])
       document.forms[0].endminute.add(new Option("", "", true, true), document.forms[0].endminute.options[0]) 
   }
   catch(e)
   { //in IE, try the below version instead of add()
       document.forms[0].starthour.add(new Option("", "", true, true), 0) //add blank option to beginning of starthour
       document.forms[0].startminute.add(new Option("", "", true, true), 0)
       document.forms[0].endhour.add(new Option("", "", true, true), 0) 
       document.forms[0].endminute.add(new Option("", "", true, true), 0)
   }
}
clearTimes();

The options available are:

document.forms[0].starthour.add(new Option(Display text, Store value, defaultSelected, selected), document.forms[0].starthour.options[0])