How can i get sysid to change to String?

Question

I need to know what's the best way to change sysid in ServiceNow to string so i can display in a field? I have a script that is concatenating reference fields and responds with Sys id i need to change that to a string to display within a field i have.

// OnChangeClientScript
var grade = g_form.getValue('u_grade');
var step = g_form.getValue('u_step');

var gradestep = g_form.getValue(grade);
gradestep = g_form.setValue('u_grade_step',grade +step);

if(gradestep != '') {
  g_form.addInfoMessage(gradestep);
}