How To Capture Form Data using OnChange

I built up a page on my website as a place to perform testing of functions that I write (30 or 40 of them to date). I use a drop-down box to list the functions out by function name. When one of them is selected, I use an onChange with “window.location” to fire that function via a Select Case structure, passing the index on the query string via this.selectedIndex in the OnChange. All of this worked fine until I decided that I would also like the value of the selected option (name of the function being tested) as well (not just the index value). I found through study that the window.location does not post any form values back, so they are not available. I kept on researching and found that the “location.reload” is supposed to post back the data, but that doesn’t work either.

So, I figured that I could pass the option value data via the query string perhaps by using “this.selectedOptions”, but that doesn’t work either. I have cut and paste a snippet of the code below, which again, works fine, but I can’t get the text value of the selected option.

enter code here
<form name="ThisForm" action="<%=Request.ServerVariables("SCRIPT_NAME")%> method="post">

            <b>Select Test Category:<b>&nbsp;
                            
            <select class="rounded" name="cboSearchCategories" id="cboSearchCategories" onChange='window.location="<%=sRootDomain%>/testcode/template/testcodepage.asp?TestCategory=" + this.selectedIndex;'                
                <option value="Select One">Select One</option>
                <option value="SearchEquipmentDB()">SearchEquipmentDB()-Case #1</option>
                <option value="DisplaySingleItem()">DisplaySingleItem()-Case #2</option>
                <option value="CreateJSONSchema()">CreateJSONSchema()-Case #3</option>
                <option value="UnlockChilkatAPI()">UnlockChilkatAPI()-Case #4</option>
            </select>
</form>

Please let me know if there is a way to make this work, without using a submit button. Much appreciated! Note that this code is written using ASP Classic, but would be pertinent for any form submission.