Listening to Events

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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.

Read the documentation.

TypeScript

// 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.

let rectangle: google.maps.Rectangle;
let map: google.maps.Map;

let infoWindow: google.maps.InfoWindow;

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

  const bounds = {
    north: 44.599,
    south: 44.49,
    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. */
function showNewRect() {
  const ne = rectangle.getBounds()!.getNorthEast();
  const sw = rectangle.getBounds()!.getSouthWest();

  const 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);
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;
index.ts

JavaScript

// 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.
let rectangle;
let map;
let infoWindow;

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

  const bounds = {
    north: 44.599,
    south: 44.49,
    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. */
function showNewRect() {
  const ne = rectangle.getBounds().getNorthEast();
  const sw = rectangle.getBounds().getSouthWest();
  const 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);
}

window.initMap = initMap;
index.js

CSS

/* 
 * 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.css

HTML

<html>
  <head>
    <title>Listening to Events</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
      The `defer` attribute causes the callback to execute after the full HTML
      document has been parsed. For non-blocking uses, avoiding race conditions,
      and consistent behavior across browsers, consider loading using Promises
      with https://www.npmjs.com/package/@googlemaps/js-api-loader.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>
index.html

Try Sample

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application. 

  git clone -b sample-rectangle-event https://github.com/googlemaps/js-samples.git
  cd js-samples
  npm i
  npm start

Other samples can be tried by switching to any branch beginning with sample-SAMPLE_NAME. 

  git checkout sample-SAMPLE_NAME
  npm i
  npm start