App developer

Hi I am a web developer,I design websites,some mobile apps and few software,lately I was building a geolocation app kind of like uber but I encountered a problem that I need help with,it is not a complex problem but I would like some help on that,I am using a platform called [login to view URL] that uses mostly Javascript.I have two apps,app A ,the driver one which sends coordinates of the driver current position in the database after every 10 seconds,App B is the user app which retrieves the current location of a driver,what i did is to get the list over the coordinates from a driver then set 2 parameter to get the current location,the parameters are sort used to get the very last coordinates,limit to get only one coordinates at a time but when I use the limit coordinates logically it gives me one coordinates but it messes up the map,the map turns grey so there is no street avenue showing until i zoom out so that is the problem.I hope you could help me