Updating Google Map Markers (UGMM)

Hi guys, please help me. The story is that I am working on a thesis with the theme of Geographic Information Systems (GIS), I use javascript as a server-side programming language that runs on the Google App Script service. But as usual, my journey in working on this assignment was not as smooth as black pink thighs.

When the coordinate points have been updated on the server side, it turns out that on the client side they are not completely updated visually, so the old points are still left.

Well, I tried a little tricky to fix it by deleting all the old coordinate points, then installing them with the new ones. But how do I do it? Please enlighten me, thank you.

A glimpse of my code,

var map;
var marker;
google.maps.event.addDomListener(window, 'load', initialize);
function initialize(){
    var bounds = new google.maps.LatLngBounds();
    map=new google.maps.Map(document.getElementById("map-canvas"));
    updateMarkers(bounds,map);

    google.maps.event.addDomListener(map,'dragend',function() {
        if($('#redo_search_in_map').is(":checked")){
            formlat = map.getCenter().lat();
            formlng = map.getCenter().lng();
            var type = $("#types").val();
            var keywords=new Array();
            $(".Check").each(function(){
                if($(this).is(":checked")){
                    keywords.push($(this).val());
                }
            });
            $.ajax({
                url:ajax_url+'listing/search_listings',
                data:{
                    'formlat':formlat,
                    'formlng':formlng,
                    'type':type,
                    'keywords':keywords
                },
                type:"get",
                success:function(resp)
                {
                    $("#ajax_listing").html(resp);
                    deleteMarkers();
                    updateMarkers(bounds,map);
                    return false;
                },
                error: function()
                {
                    alert('error');
                }
            });
            return false;
        }
    })

}

function updateMarkers(bounds, map){
    $records){ ?>
        var lat = '';
        var longi = '';
        var latlng = new google.maps.LatLng(lat, longi);
        marker = new google.maps.Marker({
            position:new google.maps.LatLng(lat,longi),
        });
        marker.setMap(map);
        bounds.extend(latlng);

    map.fitBounds(bounds);
}

function deleteMarkers(){
    marker.setMap(null);
}setMapOnAll(null);
clearMarkers();
markers = [];

You can use one of these 2 ways.

1. Set the map value to null

var map;
var marker;
google.maps.event.addDomListener(window, 'load', initialize);
function initialize(){
    var bounds = new google.maps.LatLngBounds();
    map=new google.maps.Map(document.getElementById("map-canvas"));
    updateMarkers(bounds,map);

    google.maps.event.addDomListener(map,'dragend',function() {
        if($('#redo_search_in_map').is(":checked")){
            formlat = map.getCenter().lat();
            formlng = map.getCenter().lng();
            var type = $("#types").val();
            var keywords=new Array();
            $(".Check").each(function(){
                if($(this).is(":checked")){
                    keywords.push($(this).val());
                }
            });
            $.ajax({
                url:ajax_url+'listing/search_listings',
                data:{
                    'formlat':formlat,
                    'formlng':formlng,
                    'type':type,
                    'keywords':keywords
                },
                type:"get",
                success:function(resp)
                {
                    $("#ajax_listing").html(resp);
                    deleteMarkers();
                    updateMarkers(bounds,map);
                    return false;
                },
                error: function()
                {
                    alert('error');
                }
            });
            return false;
        }
    })

}

function updateMarkers(bounds, map){
    $records){ ?>
        var lat = '';
        var longi = '';
        var latlng = new google.maps.LatLng(lat, longi);
        marker = new google.maps.Marker({
            position:new google.maps.LatLng(lat,longi),
        });
        marker.setMap(map);
        bounds.extend(latlng);

    map.fitBounds(bounds);
}

function deleteMarkers(){
    marker.setMap(null);
}setMapOnAll(null);
clearMarkers();
markers = [];

2. Clean the marker

var map;
var marker;
google.maps.event.addDomListener(window, 'load', initialize);
function initialize(){
    var bounds = new google.maps.LatLngBounds();
    map=new google.maps.Map(document.getElementById("map-canvas"));
    updateMarkers(bounds,map);

    google.maps.event.addDomListener(map,'dragend',function() {
        if($('#redo_search_in_map').is(":checked")){
            formlat = map.getCenter().lat();
            formlng = map.getCenter().lng();
            var type = $("#types").val();
            var keywords=new Array();
            $(".Check").each(function(){
                if($(this).is(":checked")){
                    keywords.push($(this).val());
                }
            });
            $.ajax({
                url:ajax_url+'listing/search_listings',
                data:{
                    'formlat':formlat,
                    'formlng':formlng,
                    'type':type,
                    'keywords':keywords
                },
                type:"get",
                success:function(resp)
                {
                    $("#ajax_listing").html(resp);
                    deleteMarkers();
                    updateMarkers(bounds,map);
                    return false;
                },
                error: function()
                {
                    alert('error');
                }
            });
            return false;
        }
    })

}

function updateMarkers(bounds, map){
    $records){ ?>
        var lat = '';
        var longi = '';
        var latlng = new google.maps.LatLng(lat, longi);
        marker = new google.maps.Marker({
            position:new google.maps.LatLng(lat,longi),
        });
        marker.setMap(map);
        bounds.extend(latlng);

    map.fitBounds(bounds);
}

function deleteMarkers(){
    marker.setMap(null);
}setMapOnAll(null);
clearMarkers();
markers = [];

You can read the complete documentation  HERE .