Google map Js API infowindow array

InfowindowDemo

var map;
var infowindow;
var locations = [
    {lat: 52.511, lng: 13.447},
    {lat: 52.549, lng: 13.422},
    {lat: 52.497, lng: 13.396},
    {lat: 52.517, lng: 13.394}
];
var contents = [
    "aaa",
    "bbb",
    "ccc",
    "ddd"
];

function initMap() {
    var latlng = {lat: 52.511, lng: 13.447};
    var mapOptions = {
        center: latlng,
        zoom: 10
    };
    map = new google.maps.Map(document.getElementById('map'), mapOptions);
    infowindow = new google.maps.InfoWindow();
    for (var i = 0; i < locations.length; i++) {
        createMarker(locations[i], contents[i]);
    }
}

function createMarker(location, content) {
    var marker = new google.maps.Marker({
        position: location,
        map: map
    });
    marker.addListener('click', function() {
       infowindow.setContent(content);
       infowindow.open(map, this);
    });
}

// https://stackoverflow.com/questions/12087212/an-array-of-infowindow-in-google-maps-api
// https://developers.google.com/maps/articles/phpsqlsearch_v3#creating-the-map