Question

I want to find out using the API if a marker has been placed on google maps at a given LatLng. Is this possible without me saving all the latlngs at which the placemarker is placed?

Answer 1

No. The API doesn’t track your markers, so you will need to track them yourself. I suggest adding each location to an array, and then writing a function which can check whether any marker in that array is located at a specific lat/lng.

Something like:

var marker_locations = [];

function addMarker(latlng) {
   marker = new google.maps.Marker(....);
   marker.setMap(map);
   marker_locations.push(latlng);
}

function markerAtPoint(latlng) {
  for (var i = 0; i < marker_locations.length; ++i) {
    if (marker_locations[i].equals(latlng)) return true;
  }
  return false;
}