The window.navigator property exposed by browsers points to a Navigator object which is a container object that makes a lot of Web Platform APIs available to us.

The standard and widely implemented properties include:

  • cookieEnabled true if cookies are enabled
  • geolocation points to the Geolocation object used by the Geolocation API
  • language returns a string representing the language currently active in the browser
  • onLine returns true if the browser is online (the browsers interpret this in different ways, be aware)
  • serviceWorker the ServiceWorkerContainer object assigned to the document (see Service Workers)
  • userAgent the name of the User Agent identifier of the browser

The standard methods include:

  • registerProtocolHandler() a way to let websites register as handlers for protocols.

There are many more methods and properties which are provided by APIs that are either experimental or implemented as drafts and not yet finalized, or just available on a tiny fraction of browsers, so I haven’t included them here but you can explore them all on MDN.