Listening to Events

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 innerMap: google.maps.Map;

let infoWindow: google.maps.InfoWindow;

async function initMap(): Promise<void> {
  await google.maps.importLibrary("maps");

  const mapElement = document.querySelector('gmp-map') as google.maps.MapElement;
  innerMap = mapElement.innerMap;

  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(innerMap);

  // 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(innerMap);
}

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 innerMap;
let infoWindow;
async function initMap() {
    await google.maps.importLibrary("maps");
    const mapElement = document.querySelector('gmp-map');
    innerMap = mapElement.innerMap;
    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(innerMap);
    // 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(innerMap);
}
initMap();
index.js

CSS

/* 
 * 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>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
    <!-- prettier-ignore -->
    <script>(g=>{var h,a,k,p="The Google Maps JavaScript API",c="google",l="importLibrary",q="__ib__",m=document,b=window;b=b[c]||(b[c]={});var d=b.maps||(b.maps={}),r=new Set,e=new URLSearchParams,u=()=>h||(h=new Promise(async(f,n)=>{await (a=m.createElement("script"));e.set("libraries",[...r]+"");for(k in g)e.set(k.replace(/[A-Z]/g,t=>"_"+t[0].toLowerCase()),g[k]);e.set("callback",c+".maps."+q);a.src=`https://maps.${c}apis.com/maps/api/js?`+e;d[q]=f;a.onerror=()=>h=n(Error(p+" could not load."));a.nonce=m.querySelector("script[nonce]")?.nonce||"";m.head.append(a)}));d[l]?console.warn(p+" only loads once. Ignoring:",g):d[l]=(f,...n)=>r.add(f)&&u().then(()=>d[l](f,...n))})
    ({key: "AIzaSyA6myHzS10YXdcazAFalmXvDkrYCp5cLc8", v: "weekly" });</script>
  </head>
  <body>
    <gmp-map center="44.5452,-78.5389" zoom="9" map-id="DEMO_MAP_ID"></gmp-map>
  </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 https://github.com/googlemaps-samples/js-api-samples.git
  cd samples/rectangle-event
  npm i
  npm start