How to set markers for a specific map in google maps?

Question

Google

Several Google maps are connected on the page, no more than two markers can be placed on each. Cards are added by the user, so the number is not known in advance. I figured out how to add markers to a specific map, but I can’t figure out how to get markers for only a specific map later. Here is an example code:

var map = Array();
var directionsDisplay = Array();
var markers = Array();

function handleApiReady(map_id) {
  var myLatlng = new google.maps.LatLng(56.323678, 44.0);
  var myOptions = {
    zoom: 12,
    disableDefaultUI: true,
    center: myLatlng,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  
  map[map_id] = new google.maps.Map(document.getElementById("waymap_"+map_id+""), myOptions);	
  
  directionsDisplay[map_id]=new google.maps.DirectionsRenderer();
  map[map_id].addListener('click', function(event) {
    if(markers.length>1){
      deleteMarkers(map_id);
    }
    addMarker(event.latLng,map_id);
  });
}

// Adds a marker to the map and push to the array.
function addMarker(location,map_id) {
  var lat, lng;

  var marker = new google.maps.Marker({
    position: location,
    map: map[map_id]
  });
  lng=marker.getPosition().lng();
  lat=marker.getPosition().lat();
  
  markers.push(marker);
}

I tried to make this line:
if(markers[map_id].length>1){
deleteMarkers(map_id);
}
but an error occurs