JSFiddle - React, Tailwind, and code Playground

JavaScript

function initialize() {
    var center = new google.maps.LatLng(49.9, 15.5);
    var lastInfoWindow = null;

    var map = new google.maps.Map(document.getElementById('map'), {
        zoom: 8,
        center: center,
        mapTypeId: google.maps.MapTypeId.ROADMAP,
		scrollwheel: false
    });


    var markers = [];
    var max = data.photos.length; 
    for (var i = 0; i < max; i++) {
        (function(index) {
            var dataPhoto = data.photos[i];
            var latLng = new google.maps.LatLng(dataPhoto.latitude, dataPhoto.longitude);
            var marker = new google.maps.Marker({
                position: latLng,
                icon: '/wp-content/themes/default/img/home-icon.png'
            });

            var contentString = '<div class="mapcontent">' +
                    '<a href="' + dataPhoto.link + '"><h5>' + dataPhoto.title + '</h5></a>' +
                    '' +
                    '<a href="' + dataPhoto.link + '"><img src="' + dataPhoto.photo_file_url + '"/></a><p></p>' +
                    '<a href="' + dataPhoto.link + '" class="btn btn-primary btn-md" data-toggle="modal">Zobrazit detaily</a>' +
                    '' +
                    '</div>';
            var infowindow = new google.maps.InfoWindow({
                content: contentString,
            });
            marker.addListener('click', function () {
                if(lastInfoWindow!==null) {
                    lastInfoWindow.close();
                }
                infowindow.open(map, marker);
                lastInfoWindow = infowindow;
            });


            markers.push(marker);
        })(i);
    }
    var clusterStyles = [
        {
            textColor: 'white',
            url: '/wp-content/themes/default/img/home-icon3.png',
            height: 48,
            width: 48
        },
        {
            textColor: 'white',
            url: '/wp-content/themes/default/img/home-icon3.png',
            height: 48,
            width: 48
        },
  ...