…looking at your code more closely, this is probably the way you want to go
var fieldname = globals.gElementName
var dataproviderName = elements[fieldname].getDataProviderID()//get name of the dataprovider attached to this element.
controller.setDataProviderValue(dataproviderName, "test")
Then probably the value of your global that goes into var fieldname doesn’t exist as an element on your form .
1)Make sure the dataprovider (eg. textfield) you are trying to set , has a name-property entered (eg. “myTarget”), in order to make it appear as an element.
2) Test your script by doing.
var fieldname = "myTarget"
var dataproviderName = elements[fieldname].getDataProviderID()
controller.setDataProviderValue(dataproviderName, "test")