text: function updateDatabase(latitude, longitude) {
  
      if (currentUser != null) {
          firebase.database().ref('/users/' + currentUser.uid).set({
              Latitude: latitude,
              Longitude: longitude,
              Timestamp: "" + new Date(),
              Name: currentUser.displayName
          });
          
          console.log("db update");
          console.log(latitude,longitude);
      }
      else
          alert("DB update : user null error");
  }
  