module.exports = function() {
  // Borrowed wholesale from https://github.com/defunkt/jquery-pjax
  return window.history &&
    window.history.pushState &&
    window.history.replaceState &&
    // pushState isn’t reliable on iOS until 5.
    !navigator.userAgent.match(/((iPod|iPhone|iPad).+\bOS\s+[1-4]|WebApps\/.+CFNetwork)/)
}