To retrieve the performer name who completed the workitem in the post script of the workstep Ws1,utilize the below code snippet.
var session = blserver.connect("ebms","ebms");
var wsi = blserver.getWorkStepInstance(session, jst.getProcessInstanceID(),jst.getWorkstepName());
var plst = wsi.getCompletedWorkItemPerformer(); // The above API will return list of performer for this workitem. The workitem may have gone through number of cycle/rollback and the list contains all the performer.
var performer = plst.get(plst.size()-1); // The last value is performer of this workitem completed just now.
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