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Getting Properties With Event Handlers

  • This example demonstrates how to listen for thezoom_changed event on a Google Map.

  • When the zoom level changes, an info window updates to display the current zoom level.

  • The sample code uses the Google Maps JavaScript API and is provided in both TypeScript and JavaScript.

  • Users can interact with a live demo via JSFiddle or Google Cloud Shell, and the code can be cloned for local execution.

This example listens for thezoom_changed event and updates an infowindow when the zoom level changes.

Read thedocumentation.

TypeScript

asyncfunctioninitMap(){// Request needed libraries.const{Map}=awaitgoogle.maps.importLibrary("maps")asgoogle.maps.MapsLibrary;constoriginalMapCenter=newgoogle.maps.LatLng(-25.363882,131.044922);constmap=newgoogle.maps.Map(document.getElementById("map")asHTMLElement,{zoom:4,center:originalMapCenter,});constinfowindow=newgoogle.maps.InfoWindow({content:"Change the zoom level",position:originalMapCenter,});infowindow.open(map);map.addListener("zoom_changed",()=>{infowindow.setContent("Zoom: "+map.getZoom()!);});}initMap();
Note: Read theguide on using TypeScript and Google Maps.

JavaScript

asyncfunctioninitMap(){// Request needed libraries.const{Map}=awaitgoogle.maps.importLibrary("maps");constoriginalMapCenter=newgoogle.maps.LatLng(-25.363882,131.044922);constmap=newgoogle.maps.Map(document.getElementById("map"),{zoom:4,center:originalMapCenter,});constinfowindow=newgoogle.maps.InfoWindow({content:"Change the zoom level",position:originalMapCenter,});infowindow.open(map);map.addListener("zoom_changed",()=>{infowindow.setContent("Zoom: "+map.getZoom());});}initMap();
Note: The JavaScript is compiled from the TypeScript snippet.

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;}

HTML

<html>  <head>    <title>Getting Properties With Event Handlers</title>    <link rel="stylesheet" type="text/css" href="./style.css" />    <script type="module" src="./index.js"></script>  </head>  <body>    <div></div>    <!-- 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: "AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg", v: "weekly"});</script>  </body></html>

Try Sample

Clone Sample

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

gitclone-bsample-event-propertieshttps://github.com/googlemaps/js-samples.gitcdjs-samplesnpminpmstart

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

gitcheckoutsample-SAMPLE_NAMEnpminpmstart

Except as otherwise noted, the content of this page is licensed under theCreative Commons Attribution 4.0 License, and code samples are licensed under theApache 2.0 License. For details, see theGoogle Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-10-31 UTC.