infowindow close

HTML

<script src="//maps.google.com/maps/api/js?sensor=false"></script>
<div id="map_canvas"></div>

CSS

#map_canvas {
    float: left;
    height: 565px;
    width: 100%;
}
#content {
    min-width: 320px;
}

JavaScript

var mylatlongs = [
                            {"rank":1,"name":"name 1","lat":"-25.901820984476252","lng":"135"},
                            {"rank":2,"name":"name 2","lat":"-25.901820984476252","lng":"135.05"},
                            {"rank":3,"name":"name 3","lat":"-25.901820984476252","lng":"135.025"}
                        ];
        var infowindow = null;
        jQuery(function() {
              
        
                var StartLatLng = new google.maps.LatLng(mylatlongs[0]['lat'], mylatlongs[0]['lng']);
                var mapOptions = {
                    center: StartLatLng,
                    streetViewControl: false,
                    panControl: false,
                    maxZoom:17,
                    zoom : 13,
                    zoomControl:true,
                    zoomControlOptions: {
                        style:google.maps.ZoomControlStyle.SMALL
                    }
                };

            var map = new google.maps.Map(document.getElementById('map_canvas'), mapOptions);

            var infowindow = new google.maps.InfoWindow({
                content: ''
            });
            
            jQuery.each( mylatlongs, function(i, m) {
                var StartLatLng = new google.maps.LatLng(-25.901820984476252, 134.00135040279997);

                var marker = new google.maps.Marker({
                    position: new google.maps.LatLng(m.lat, m.lng),
                    bounds: true,
                    id : 'mk_' + m.rank,
                    letter : m.index,
                    map: map,
                    title: m.name
                });

                google.maps.event.addListener(marker, 'click', function() {
                    infowindow.close();
                    infowindow.setContent(contentString);
                    infowindow.open(map,marker);
                });

                var contentString = '<div id="content">'+
                  '<div id="siteNotice">'+
                  '</div>'+
    ...