function initMap() {
    var coordinates = {lat: 51.517819, lng: -0.111853},
        map = new google.maps.Map(document.getElementById('map'), {
            center: coordinates,
            disableDefaultUI: false,
            scrollwheel: false,
            zoom: 8
        });
    $.getJSON("map.json", function (data) {
        map.setOptions({styles: data});
    });
}
google.maps.event.addDomListener(window, "load", initMap);