How to populate a dropdown box based on a selection in another Dropdown box.

Question

I am trying to find out a way to do the following:
I am using coldfusion ....working on a form. The form has
couple of dropdown boxes. Based on the selection on the first
dropdown box another dropdown box needs to get populated with
different options. These options will be coming from a query. I am
trying to find out the Javascript code for doing this.
Thanks in advance.

Answer 1

jchopra,
There's a method to doing what you're wanting to do that I've
used extensively.
Basically, within my code, I start by invoking the method
that returns the data for the dropdown lists. Then, I use the
following code to pour the data returned into a javascript array:
var locArray = new Array(#evaluate(locs.recordcount+1)#);
locArray[0] = new Array('','','','','','','','','',);
<cfloop query="locs">
locArray[#locs.CurrentRow#] = new
Array('#JSStringFormat(locationId)#',
'#JSStringFormat(fkyPolicyId)#',
'#JSStringFormat(locationNumber)#',
'#JSStringFormat(description)#',
'#JSStringFormat(address1)#',
'#JSStringFormat(address2)#',
'#JSStringFormat(zipcode)#',
'#JSStringFormat(city)#',
'#JSStringFormat(state)#';
</cfloop>
Then I wrote a javascript function that is assigned to the
first dropdown's onChange() event. When the user changes the value
that is selected within the dropdown, I use javascript to locate
(using the policyid) the corresponding record in the javascript
array and populate and/or select the appropriate value(s) in the
second dropdown.
If the data returned from the method invocation is too large
to use within a javascript array, you may need to limit the results
that are returned.
Hope this makes sense. If not, please let me know.
ds