OpenAir Scripting: How to get a value from a custom dropdown field (Hierarchy)

Our client has a requirement to get the value of a dropdown field (hierarchy) from a project record, load the hierarchy node then get the value from a custom field inside the hierarchy node. I tried to use the following codes but it always returns null. Is there a way to list the available custom fields including the hierarchies upon loading the record? How do I get the actual value of the dropdown field so that I would know which hierarchy and hierarchy node to load?

     var newr = NSOA.form.getNewRecord();

     var projectId = newr.id;

    var custid                      = newr.customer_id;