how to find xfa subform field type e.g is it a text field

I want to be able to test all fields in an XFA subform to see what kind of fields they are.

I found the code below on the forums that cycles through nodes in a subform and prints the names of the fields. I'd like to cycle the nodes and work out which are text fields, checkboxes etc so I can then reset them all to blank. Can someone tell me how?

Thanks.

var oNodes = mySubForm.nodes;
var nodesLength = oNodes.length;
for (var i = 0; i < nodesLength; i++) {
xfa.host.messageBox(oNodes.item(i).name)
}