/** No changes needed to default variables **/

                        
                    

                        
var map;
var marker;

function initMap()
{
    let location = {lat: 40.730610, lng: - 73.935242};

    map = new google.maps.Map(document.getElementById('map'), {
        center: location,
        zoom: 10,
        styles: [
            {
                "featureType": "all",
                "elementType": "labels.text.fill",
                "stylers": [
                    {
                        "saturation": 36
                    },
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 40
                    }
                ]
            },
            {
                "featureType": "all",
                "elementType": "labels.text.stroke",
                "stylers": [
                    {
                        "visibility": "on"
                    },
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 16
                    }
                ]
            },
            {
                "featureType": "all",
                "elementType": "labels.icon",
                "stylers": [
                    {
                        "visibility": "off"
                    }
                ]
            },
            {
                "featureType": "administrative",
                "elementType": "geometry.fill",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 20
                    }
                ]
            },
            {
                "featureType": "administrative",
                "elementType": "geometry.stroke",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 17
                    },
                    {
                        "weight": 1.2
                    }
                ]
            },
            {
                "featureType": "landscape",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 20
                    }
                ]
            },
            {
                "featureType": "poi",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 21
                    }
                ]
            },
            {
                "featureType": "road.highway",
                "elementType": "geometry.fill",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 17
                    }
                ]
            },
            {
                "featureType": "road.highway",
                "elementType": "geometry.stroke",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 29
                    },
                    {
                        "weight": 0.2
                    }
                ]
            },
            {
                "featureType": "road.arterial",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 18
                    }
                ]
            },
            {
                "featureType": "road.local",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 16
                    }
                ]
            },
            {
                "featureType": "transit",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 19
                    }
                ]
            },
            {
                "featureType": "water",
                "elementType": "geometry",
                "stylers": [
                    {
                        "color": "#000000"
                    },
                    {
                        "lightness": 17
                    }
                ]
            }
        ],
    });
    marker = new google.maps.Marker({
        position: location,
        map: map,
        icon: '/assets/images/map-marker.png',
    });
}
 <script src = "https://maps.googleapis.com/maps/api/js?key=AIzaSyBXC8PsxjBlXrRXHsMunDmZ_PTQh1KRCQA&callback=initMap"
         async defer></script>