CODE EXAMPLE FOR JAVASCRIPT

add and remove multiple markers on google maps js

    <script defer src="https://maps.googleapis.com/maps/api/js?language=en&key=your_api_key" type="text/javascript"></script>
<script>

    $(function(){
        var map;
        var markersArray = [];
        var markersOnMap;
        var bounds = new google.maps.LatLngBounds();
        var loc;

        var InforObj = [];

        var mapOptions = { mapTypeId: google.maps.MapTypeId.ROADMAP };

        map =  new google.maps.Map(document.getElementById("drivers-map"), mapOptions);

        window.onload = function() {
            renderMapWithDetail();
            setInterval(() => {
                renderMapWithDetail();
                removeMarkers();
            }, 10000);
        };

        function renderMapWithDetail() {
            $.get('your_route_to_get_maps_data', function(data) {
                markersOnMap = data.markers_on_map;
                for (var i = 0; i < markersOnMap.length; i++) {
                    if (markersOnMap[i].LatLng[0].lat !== null && markersOnMap[i].LatLng[0].lng !== null) {
                        var contentString = `<div id="content">
                                                <img src="${ markersOnMap[i].img_url} " width="50" >
                                                <h5> ${markersOnMap[i].driverName}</h5>
                                                <p class="company-name-map-window">Company: ${markersOnMap[i].providerName}</p>
                                                <a href="${markersOnMap[i].stream_route}" class="btn btn-dark btn-sm">
                                                    <i class="fa fa-video"></i>
                                                </a>
                                            </div>`;
                        addMarker(markersOnMap[i].LatLng[0], contentString);
                    }
                }
            map.fitBounds(bounds);
            map.panToBounds(bounds);
            });

        }

        function addMarker(location, contentString) {
            console.log(location);
            var marker = new google.maps.Marker({
                position: location,
                map: map,
            });
            const infowindow = new google.maps.InfoWindow({
                content: contentString,
                maxWidth: 300
            });

            marker.addListener('click', function() {
                closeOtherInfo();
                infowindow.open(marker.get('map'), marker);
                InforObj[0] = infowindow;
            });
            markersArray.push(marker)
            loc = new google.maps.LatLng(marker.position.lat(), marker.position.lng());
            bounds.extend(loc);
        }

        function closeOtherInfo() {
            if (InforObj.length > 0) {
                /* detach the info-window from the marker ... undocumented in the API docs */
                InforObj[0].set("marker", null);
                /* and close it */
                InforObj[0].close();
                /* blank the array */
                InforObj.length = 0;
            }
        }

        function removeMarkers() {
            for (var i = 0; i < markersArray.length; i++ ) {
                markersArray[i].setMap(null);
            }
            markersArray.length = 0;
        }

    });
</script>