/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

module.exports = function headersMiddleware(req, res, next){
  res.on('header', function() {
    if (res.statusCode === 200 || res.statusCode === 401) {
      res.setHeader('X-Timestamp', new Date().getTime());
    }
  });
  next();
};

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

module.exports = function headersMiddleware(req, res, next){
  res.once('header', function() {
    if (res.statusCode === 200 || res.statusCode === 401) {
      res.setHeader('X-Timestamp', new Date().getTime());
    }
  });
  next();
};

Use once instead of on to run the event only once.