Auto populate the Assigned vendor field based on assignment group on work order task( wm_task)

[Community Alums]

I want to auto-populate the assigned vendor (assigned_vendor) when the assignment group changes on work order task ( wm_task) but onchange script is not working.

script:

field: assignment group

function onChange(control, oldValue, newValue, isLoading) {

    if (isLoading || newValue == '')

        return;

    var assignedvendor = g_form.getValue("assigned_vendor");

    if (assignedvendor == "") {

        var assignmentgrp = g_form.getReference("assignment_group");

        if (assignmentgrp != null)

            g_form.setValue('assigned_vendor', assignmentgrp.vendors.toString());

            g_form.setMandatory('assigned_vendor',true);

    }

}

Assigned vendor: 
reference qualifier: javascript:'sys_idIN' + current.assignment_group.vendors

issue: it's not immediately clearing the value of assigned vendor on work order task(wm_task).

any help on this really appreciated!

[Zach Koch]

Are you saying it is working, but not when the form loads? If so remove the isLoading from the if block

  if (isLoading || newValue == '')

        return;