If else condition for asssociated values ArcGIS JS API Application

[GeoffreyWest]

I have an application where I would like to create a workflow where users must select a request type and in order to submit a request, at least one of the affiliated request type subcategories must be selected. 

I am using 2 sets of combo boxes; one with my "main" request type, and other with my "subcategory"

So if i.e. E-WASTE is chosen in my "main" request type, before an order can be submitted, the E-WASTE "subcategory" combo box must have a value selected.

Here is a start with a function validating my request type and prohibiting the user from continuing unless a value is chosen, I'd like to extend this based on the values chosen in "cbRequestType"

function ValicateRequestData() {
    if (dijit.byId("cbRequestType").getValue() == "") {
        ShowSpanErrorMessage("spanServiceErrorMessage", messages.getElementsByTagName("spanErrorMsgType")[0].childNodes[0].nodeValue);
        return false;
    }


    if (dijit.byId("cbRequestType").getValue() == "") {
        ShowSpanErrorMessage("spanServiceErrorMessage", messages.getElementsByTagName("spanErrorMsgType")[0].childNodes[0].nodeValue);
        return false;
    }