map_test.html

<!DOCTYPE html>
<html>
  <head>
    <title>Getting LatLng from a Click Event</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <style>
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }
      /* Optional: Makes the sample page fill the window. */
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
	<input type="hidden" id="latlong" value="">
	<input type="hidden" id="debug" value="">
    <script>
	var map ;
	var infoWindow;

      function initMap() {
        var myLatlng = {lat: -25.363, lng: 131.044};

        map = new google.maps.Map(
            document.getElementById('map'), {zoom: 15, center: myLatlng});

        // Create the initial InfoWindow.
		 google.maps.event.addListenerOnce(map, 'idle', function () {
			document.getElementById("debug").value = 1256;
		});

        infoWindow = new google.maps.InfoWindow(
            {content: 'Click the map to get Lat/Lng info!', position: myLatlng});
        infoWindow.open(map);

        // Configure the click listener.
        map.addListener('click', function(mapsMouseEvent) {
          // Close the current InfoWindow.
          infoWindow.close();


          // Create a new InfoWindow.
          infoWindow = new google.maps.InfoWindow({position: mapsMouseEvent.latLng});
          infoWindow.setContent(mapsMouseEvent.latLng.toString());
		  document.getElementById("latlong").value = mapsMouseEvent.latLng.toString();
          infoWindow.open(map);
        });
      }

	function zoomtolocation(lats,longs) {
		map.setCenter(new google.maps.LatLng(lats,longs));
	}

	function infowindowshow(lats,longs,contentman){
		infoWindow.close();
		var infowindowm = new google.maps.InfoWindow({
			content: contentman
		});
		infowindowm.setPosition({lat: lats, lng: longs});
		infowindowm.open(map);
		}


	function drawcircle(tit,lat,lng,rad,colr,opac){

		  // Create marker
		var marker = new google.maps.Marker({
			map: map,
			position: new google.maps.LatLng(lat, lng),
			title: tit
		});

		// Add circle overlay and bind to marker
		var circle = new google.maps.Circle({
			map: map,
            strokeColor: "#FFFFFF",
            strokeOpacity: 0.8,
            strokeWeight: 2,
            fillColor: colr,
            fillOpacity: opac,
			radius: rad
		});

		circle.bindTo('center', marker, 'position');
	}
    </script>
    <script async defer
    src="https://maps.googleapis.com/maps/api/js?key=<key>&callback=initMap">
    </script>
  </body>
</html>