Google maps - how to add marker without layout refresh

http://stackoverflow.com/questions/29806815/google-maps-how-to-add-marker-without-layout-refresh

HTML

<script src="https://maps.googleapis.com/maps/api/js?sensor=false"></script>
<div id="map-canvas"></div>

CSS

#map-canvas {
    height: 500px;
    width: 500px;
}

JavaScript

var map, marker, myLatlng;

function initialize() {
    var mapOptions = {
        center: {
            lat: 59.424959,
            lng: 24.7382414
        },
        zoom: 12
    };

    map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);

}

google.maps.event.addDomListener(window, 'load', initialize);

setInterval(function () {

    if (!myLatlng || !myLatlng.lng) {
      myLatlng = new google.maps.LatLng(59.424959, 24.7382414);
    } else {
      myLatlng = new google.maps.LatLng(myLatlng.lat(), myLatlng.lng() + 0.01);
    }
    
    var mapOptions = {
        zoom: 12,
        center: myLatlng
    }
    // var map = new google.maps.Ma(document.getElementById("map-canvas"), mapOptions);
    if (!marker || !marker.setPosition) {
        marker = new google.maps.Marker({
            position: myLatlng,
            title: "Hello World!"
        });

        // To add the marker to the map, call setMap();
        marker.setMap(map);
    } else {
        marker.setPosition(myLatlng);
    }

}, 5000);