JSFiddle - React, Tailwind, and code Playground

HTML

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<div id="mapCanvas"></div>

CSS

#mapCanvas{width:500px;height:300px;}

JavaScript

var markers = [];
var map;

function initialize() {
    var myOptions = {
        center: new google.maps.LatLng(45.4555729, 9.169236),
        zoom: 20,
        mapTypeId: google.maps.MapTypeId.ROADMAP,

        panControl: true,
        mapTypeControl: false,
        panControlOptions: {
            position: google.maps.ControlPosition.RIGHT_CENTER
        },
        zoomControl: true,
        zoomControlOptions: {
            style: google.maps.ZoomControlStyle.LARGE,
            position: google.maps.ControlPosition.RIGHT_CENTER
        },
        scaleControl: false,
        streetViewControl: false,
        streetViewControlOptions: {
            position: google.maps.ControlPosition.RIGHT_CENTER
        }
    };
    map = new google.maps.Map(document.getElementById("mapCanvas"), myOptions);
    
    // adding 3 markers, all visible false at first
    markers.push(new google.maps.Marker({
        position: new google.maps.LatLng(45.3555629, 9.169236),
        map: map,
        visible: false
    }));
    
     markers.push(new google.maps.Marker({
        position: new google.maps.LatLng(45.4555529, 9.169236),
        map: map,
        visible: false
    }));
    
     markers.push(new google.maps.Marker({
        position: new google.maps.LatLng(45.5555429, 9.169236),
        map: map,
        visible: false
    }));

    // showing 2 out of 3 markers
    showVisible();
}

 function showVisible() {
         
     var bounds = new google.maps.LatLngBounds();
     
     // showing only 2 visible 1 hidden (because of markers.length-1)
     for(var i=0; i<markers.length-1; i++) {
      
         markers[i].setVisible(true);
         
         // extending bounds to contain this visible marker position
         bounds.extend( markers[i].getPosition() );
     }
     
     // setting new bounds to visible markers of 2
     map.fitBounds(bounds);

 }

initialize();