Map with Marker

by Vyacheslav Yashnikov

HTML

<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
<button id="level-1">Уровень 1</button>
<button id="level-2">Уровень 2</button>
<button id="level-3">Уровень 3</button><br>
<button id="msk-njk">Москва – Нижнекамск</button><p>
Время в полёте: 1 ч 45 мин
</p>
<button id="sur-njk">Стамбул – Нижнекамск</button><p>
Время в полёте: 3 ч 55 мин
</p>
<div id="map"></div>
 <!-- Replace the value of the key parameter with your own API key. -->
<script async defer
src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap">
</script>

CSS

#map {
  height: 400px;
  width: 100%;
 }
 p {
   display: inline;
 }

JavaScript

var map;
var markers = [];
var allMarkers = [];
var moscow;
var stambul;
var nijnekamsk;
var styles = [
  {
    "elementType": "geometry",
    "stylers": [
      {
        "color": "#f5f5f5"
      }
    ]
  },
  {
    "elementType": "labels.icon",
    "stylers": [
      {
        "visibility": "off"
      }
    ]
  },
  {
    "elementType": "labels.text.fill",
    "stylers": [
      {
        "color": "#616161"
      }
    ]
  },
  {
    "elementType": "labels.text.stroke",
    "stylers": [
      {
        "color": "#f5f5f5"
      }
    ]
  },
  {
    "featureType": "administrative.country",
    "elementType": "geometry.stroke",
    "stylers": [
      {
        "color": "#a3a3a3"
      }
    ]
  },
  {
    "featureType": "administrative.land_parcel",
    "elementType": "labels.text.fill",
    "stylers": [
      {
        "color": "#bdbdbd"
      }
    ]
  },
  {
    "featureType": "administrative.province",
    "elementType": "geometry.stroke",
    "stylers": [
      {
        "color": "#b2b2b2"
      }
    ]
  },
  {
    "featureType": "poi",
    "elementType": "geometry",
    "stylers": [
      {
        "color": "#eeeeee"
      }
    ]
  },
  {
    "featureType": "poi",
    "elementType": "labels.text.fill",
    "stylers": [
      {
        "color": "#757575"
      }
    ]
  },
  {
    "featureType": "poi.park",
    "elementType": "geometry",
    "stylers": [
      {
        "color": "#e5e5e5"
      }
    ]
  },
  {
    "featureType": "poi.park",
    "elementType": "labels.text.fill",
    "stylers": [
      {
        "color": "#9e9e9e"
      }
    ]
  },
  {
    "featureType": "road",
    "elementType": "geometry",
    "stylers": [
      {
        "color": "#ffffff"
      }
    ]
  },
  {
    "featureType": "road.arterial",
    "elementType": "labels.text.fill",
    "stylers": [
      {
        "color": "#757575"
      }
    ]
  },
  {
    "featureType": "road.highway",
    "elementType": "geometry",
    "stylers": [
      {
        "color": "#e8e8e8"
      }
...