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

Rectangle Events

Read the documentation or view this example fullscreen.

// This example adds a user-editable rectangle to the map.
// When the user changes the bounds of the rectangle,
// an info window pops up displaying the new bounds.

var rectangle;
var map;
var infoWindow;

function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    center: {lat: 44.5452, lng: -78.5389},
    zoom: 9
  });

  var bounds = {
    north: 44.599,
    south: 44.490,
    east: -78.443,
    west: -78.649
  };

  // Define the rectangle and set its editable property to true.
  rectangle = new google.maps.Rectangle({
    bounds: bounds,
    editable: true,
    draggable: true
  });

  rectangle.setMap(map);

  // Add an event listener on the rectangle.
  rectangle.addListener('bounds_changed', showNewRect);

  // Define an info window on the map.
  infoWindow = new google.maps.InfoWindow();
}
// Show the new coordinates for the rectangle in an info window.

/** @this {google.maps.Rectangle} */
function showNewRect(event) {
  var ne = rectangle.getBounds().getNorthEast();
  var sw = rectangle.getBounds().getSouthWest();

  var contentString = '<b>Rectangle moved.</b><br>' +
      'New north-east corner: ' + ne.lat() + ', ' + ne.lng() + '<br>' +
      'New south-west corner: ' + sw.lat() + ', ' + sw.lng();

  // Set the info window's content and position.
  infoWindow.setContent(contentString);
  infoWindow.setPosition(ne);

  infoWindow.open(map);
}
<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>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <title>Rectangle Events</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 example adds a user-editable rectangle to the map.
      // When the user changes the bounds of the rectangle,
      // an info window pops up displaying the new bounds.

      var rectangle;
      var map;
      var infoWindow;

      function initMap() {
        map = new google.maps.Map(document.getElementById('map'), {
          center: {lat: 44.5452, lng: -78.5389},
          zoom: 9
        });

        var bounds = {
          north: 44.599,
          south: 44.490,
          east: -78.443,
          west: -78.649
        };

        // Define the rectangle and set its editable property to true.
        rectangle = new google.maps.Rectangle({
          bounds: bounds,
          editable: true,
          draggable: true
        });

        rectangle.setMap(map);

        // Add an event listener on the rectangle.
        rectangle.addListener('bounds_changed', showNewRect);

        // Define an info window on the map.
        infoWindow = new google.maps.InfoWindow();
      }
      // Show the new coordinates for the rectangle in an info window.

      /** @this {google.maps.Rectangle} */
      function showNewRect(event) {
        var ne = rectangle.getBounds().getNorthEast();
        var sw = rectangle.getBounds().getSouthWest();

        var contentString = '<b>Rectangle moved.</b><br>' +
            'New north-east corner: ' + ne.lat() + ', ' + ne.lng() + '<br>' +
            'New south-west corner: ' + sw.lat() + ', ' + sw.lng();

        // Set the info window's content and position.
        infoWindow.setContent(contentString);
        infoWindow.setPosition(ne);

        infoWindow.open(map);
      }
    </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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Google Maps JavaScript API
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