JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maps.googleapis.com/maps/api/js?v=3.exp"></script>

<div id="map-canvas"></div>

CSS

html, body, #map-canvas {
        height: 100%;
        margin: 0px;
        padding: 0px
      }

JavaScript

function onLoad(){
    document.addEventListener("deviceready", onDeviceReady, false);
    }

    function onDeviceReady() {  


   }

 var map;
     function initialize() {

     var mapOptions = {
    zoom: 14  
      };
     map = new google.maps.Map(document.getElementById('map-canvas'),
      mapOptions);

     var pos = new google.maps.LatLng(37.4184,-122.0880);
     map.setCenter(pos);

  // Try HTML5 geolocation
  if(navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(function(position) {
      var pos = new google.maps.LatLng(position.coords.latitude,
                                       position.coords.longitude);

        var infowindow = new google.maps.InfoWindow({
          content: '<p><img src="posizione.png">contenuto messaggio</p>'
       });


        var marker1 = new google.maps.Marker({
           position: pos,
           map: map,
           title: 'ciao!'

     }); 

    google.maps.event.addListener(marker1, 'click', function() {
    infowindow.open(map,marker1);
    });


    var marker2 = new google.maps.Marker({
           position: new google.maps.LatLng( 45.4353135, 12.135795400000006 ),
           map: map,
           title: 'ciao!'

     }); 



      map.setCenter(pos);
    }, function() {
      handleNoGeolocation(true);
    });
  } else {
    // Browser doesn't support Geolocation
    handleNoGeolocation(false);
  }
}

function handleNoGeolocation(errorFlag) {
  if (errorFlag) {
    var content = 'Error: The Geolocation service failed.';
  } else {
    var content = 'Error: Your browser doesn\'t support geolocation.';
  }

  var options = {
    map: map,
    position: new google.maps.LatLng(60, 105),
    content: content
  };

  var infowindow = new google.maps.InfoWindow(options);
  map.setCenter(options.position);
}


google.maps.event.addDomListener(window, 'load', initialize);