Adding javascript validation using DataUtilities on create wizard

Hi all,

I have a requirement of driver and dependent attributes which is based on selection of one value from combobox other attribute values should get populated. I'm referring to this solution https://support.ptc.com/appserver/cs/view/solution.jsp?n=CS64401.

So I have created a data utilities class which is mapped to my driver attribute. And from that I can able to

call my javascript function which I have added in jsp page.

And that onchange validation also working fine. But my javascript function is not changing the value of other attribute.

Here is my javascript function.

<script type="text/javascript">
 function customChangefunction(){
 var target = window.document.getElementsByName("resultCombo");
 var src = window.document.getElementById("sampleCombo");
 var strUser = src.options[src.selectedIndex].value;
 alert(strUser);
 var colours = new Array('Black', 'White', 'Blue');
 var shapes = new Array('Square', 'Circle', 'Triangle');
 var names = new Array('John', 'David', 'Sarah');
 switch (strUser) {
 case 'one':
 target.options.length = 0;
 for (i = 0; i < colours.length; i++) {
 createOption(target, colours[i], colours[i]);
 }
 break;
 case 'two':
 target.options.length = 0; 
 for (i = 0; i < shapes.length; i++) {
 createOption(target, shapes[i], shapes[i]);
 }
 break;
 case 'three':
 target.options.length = 0;
 for (i = 0; i < names.length; i++) {
 createOption(target, names[i], names[i]);
 }
 break;
 default:
 target.options.length = 0;
 break;
 }
 }
 function createOption(ddl, text, value) {
 var opt = document.createElement("OPTION");
 opt.value = value;
 opt.text = text;
 ddl.options.add(opt);
 opt.appendChild(text);
 document.getElementById(ddl).appendChild(opt);
 }
</script>

Can some tell me this is the correct way of doing it. And why this js function not working? From onchange I'm getting

the selected value.

And I have one more doubt if my dependent attribute is already having some values will this override and populate what we give here?

Please suggest me some solution.