Remove the previous marker and add marker in the updated lat lng

Question

I have a gps device which sends data every 10 seconds. I am saving the data (lat, lng) in the MySql database., I am retrieving the data from the DB and putting the markers o

Answer 1

You have two options, both involve keeping a reference to the marker outside of the displayLocation function:

1. use the reference to move the existing marker

var marker;
function displayLocation(location) {
  console.log(location.lat)
    var position = new google.maps.LatLng(parseFloat(location.lat), parseFloat(location.lng));
    if (marker && marker.setPosition) {
      // if the marker already exists, move it (set its position)
      marker.setPosition(location);
    } else {
      // create a new marker, keeping a reference
      marker = new google.maps.Marker({
        map: map, 
        position: position,
        title: 'test!'
      });
    }
}

2. remove the existing marker from the map and create a new one

var marker;
function displayLocation(location) {
  console.log(location.lat)
    var position = new google.maps.LatLng(parseFloat(location.lat), parseFloat(location.lng));
    if (marker && marker.setMap) {
      // if the marker already exists, remove it from the map
      marker.setMap(null);
    }
    // create a new marker, keeping a reference
    marker = new google.maps.Marker({
      map: map, 
      position: position,
      title: 'test!'
    });
}

Answer 2

You should do

map.addMarker(new MarkerOptions()
        .position(new LatLng(parseFloat(location.lat), parseFloat(location.lng)))
        .title("test!"));

in displayLocation function