notifications-admin/app/assets/javascripts/cookieMessage.js

(function () {
  "use strict";

  var root = this;
  if(typeof root.GOVUK === 'undefined') { root.GOVUK = {}; }

  GOVUK.addCookieMessage = function () {
    var message = document.getElementById('global-cookie-message'),
        hasCookieMessage = (message && GOVUK.cookie('seen_cookie_message') === null);

    if (hasCookieMessage) {
      message.style.display = 'block';
      GOVUK.cookie('seen_cookie_message', 'yes', { days: 28 });
    }
  };
}).call(this);