I was developing a dynamic map in which we can create geofences, location searches and routing, but I couldn't find any navigation using HERE Maps JavaScript API? Does any one know how to do so?
Navigation is not a feature of the Maps API for JavaScript.
It is however part of the mobile SDK, since navigation use cases make more sense on mobile devices, as those are equipped with GNSS sensors. GNSS are Global Navigation Satellite Systems, like GPS, Glonass, Beidou or Galileo for example.
Assuming you're tracking location with JavaScript, you could however use the Routing feature of the Maps API for JavaScript, and some added logic of your own, to provide Navigation.