You're all set!

To start developing, please head over to our developer documentation.

Activate the Google Maps JavaScript API

To get you started we'll guide you through the Google Developers Console to do a few things first:

  1. Create or choose a project
  2. Activate the Google Maps JavaScript API and related services
  3. Create appropriate keys
Continue

Overlay map types

Read the documentation or view this example full screen.

/*
 * This demo illustrates the coordinate system used to display map tiles in the
 * API.
 *
 * Tiles in Google Maps are numbered from the same origin as that for
 * pixels. For Google's implementation of the Mercator projection, the origin
 * tile is always at the northwest corner of the map, with x values increasing
 * from west to east and y values increasing from north to south.
 *
 * Try panning and zooming the map to see how the coordinates change.
 */

/** @constructor */
function CoordMapType(tileSize) {
  this.tileSize = tileSize;
}

CoordMapType.prototype.getTile = function(coord, zoom, ownerDocument) {
  var div = ownerDocument.createElement('div');
  div.innerHTML = coord;
  div.style.width = this.tileSize.width + 'px';
  div.style.height = this.tileSize.height + 'px';
  div.style.fontSize = '10';
  div.style.borderStyle = 'solid';
  div.style.borderWidth = '1px';
  div.style.borderColor = '#AAAAAA';
  return div;
};

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 10,
    center: {lat: 41.850, lng: -87.650}
  });

  // Insert this overlay map type as the first overlay map type at
  // position 0. Note that all overlay map types appear on top of
  // their parent base map.
  map.overlayMapTypes.insertAt(
      0, new CoordMapType(new google.maps.Size(256, 256)));
}
<div id="map"></div>
/* 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;
}
<!-- Replace the value of the key parameter with your own API key. -->
<script async defer
src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap">
</script>

Try it yourself

Hover at top right of the code block to copy the code or open it in JSFiddle.

<!DOCTYPE html>
<html>
  <head>
    <title>Overlay map types</title>
    <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>
    <script>

      /*
       * This demo illustrates the coordinate system used to display map tiles in the
       * API.
       *
       * Tiles in Google Maps are numbered from the same origin as that for
       * pixels. For Google's implementation of the Mercator projection, the origin
       * tile is always at the northwest corner of the map, with x values increasing
       * from west to east and y values increasing from north to south.
       *
       * Try panning and zooming the map to see how the coordinates change.
       */

      /** @constructor */
      function CoordMapType(tileSize) {
        this.tileSize = tileSize;
      }

      CoordMapType.prototype.getTile = function(coord, zoom, ownerDocument) {
        var div = ownerDocument.createElement('div');
        div.innerHTML = coord;
        div.style.width = this.tileSize.width + 'px';
        div.style.height = this.tileSize.height + 'px';
        div.style.fontSize = '10';
        div.style.borderStyle = 'solid';
        div.style.borderWidth = '1px';
        div.style.borderColor = '#AAAAAA';
        return div;
      };

      function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 10,
          center: {lat: 41.850, lng: -87.650}
        });

        // Insert this overlay map type as the first overlay map type at
        // position 0. Note that all overlay map types appear on top of
        // their parent base map.
        map.overlayMapTypes.insertAt(
            0, new CoordMapType(new google.maps.Size(256, 256)));
      }
    </script>
    <script async defer
    src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap">
    </script>
  </body>
</html>

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