runas.js

var RunAsUtil = {
        execute: function(workFunction, runAsUser) {
            Packages.org.alfresco.repo.security.authentication.AuthenticationUtil.runAs(new Packages.org.alfresco.repo.security.authentication.AuthenticationUtil.RunAsWork() 
            {
                    doWork: workFunction
            }, runAsUser);                        
        },
     doInTransaction: function(workFunction) {
         var txs = Packages.org.springframework.web.context.ContextLoader.getCurrentWebApplicationContext().getBean("TransactionService");
         var th = txs.getRetryingTransactionHelper();
         var callback = new Packages.org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback() {
             execute: workFunction
         };
         th.doInTransaction(callback, false, true);
     }
};