How to use the docusign-esign.TemplateRole function in docusign-esign

// list of user account(s)
      // note that a given user may be a member of multiple accounts
      var loginAccounts = loginInfo.getLoginAccounts();
      console.log('LoginInformation: ' + JSON.stringify(loginAccounts));

      // ===============================================================================
      // Step 2:  Create Envelope API (AKA Signature Request) from a Template
      // ===============================================================================

      // create a new envelope object that we will manage the signature request through
      var envDef = new docusign.EnvelopeDefinition();
      envDef.setEmailSubject('Please sign this document sent from Node SDK)');
      envDef.setTemplateId(templateId);

      // create a template role with a valid templateId and roleName and assign signer info
      var tRole = new docusign.TemplateRole();
      tRole.setRoleName(templateRoleName);
      tRole.setName(signerName);
      tRole.setEmail(signerEmail);

      // create a list of template roles and add our newly created role
      var templateRolesList = [];
      templateRolesList.push(tRole);

      // assign template role(s) to the envelope
      envDef.setTemplateRoles(templateRolesList);

      // send the envelope by setting |status| to "sent". To save as a draft set to "created"
      envDef.setStatus('sent');

      // use the |accountId| we retrieved through the Login API to create the Envelope
      var loginAccount = new docusign.LoginAccount();