JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script src="http://www.sofiesrenting.com/common/calendar/ac-includes/js/jquery_ui_map/ui/jquery.ui.map.js"></script>
<div id="map_canvas" class="big_map2"></div>
<button type="button">Apanhar coordenadas</button>

CSS

.big_map2 {
    width:400px;
    height:300px;
}
button{
    float: left;
}

JavaScript

var map = new google.maps.Map(document.getElementById("map_canvas"), {
    zoom: 13,
    center: new google.maps.LatLng(-2.527066,-44.29842),
    mapTypeId: google.maps.MapTypeId.ROADMAP
});
$('button').click(coordenadas);

function coordenadas() {
    var coord = map.getCenter();
    var alerta = 'Latitude: ' + coord.d + ', longitude: ' + coord.e;
    alert(alerta);
}