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Data Layer: Dynamic Styling

  • This example demonstrates dynamic styling of KML feature objects on a map using a data layer.

  • Users can hover over features to highlight them with a thicker outline and click to change their color.

  • The sample utilizes GeoJSON data to display features and allows for customization of fill, stroke, and stroke weight.

  • Code snippets are provided in TypeScript and JavaScript, along with HTML and CSS for implementation.

This example uses a data layer to dynamically change the appearance of someKMLfeature objectswhen the user hovers over or clicks them.

Read thedocumentation.

TypeScript

letmap:google.maps.Map;functioninitMap():void{map=newgoogle.maps.Map(document.getElementById("map")asHTMLElement,{zoom:4,center:{lat:-28,lng:137},});// Load GeoJSON.map.data.loadGeoJson("https://storage.googleapis.com/mapsdevsite/json/google.json");// Color each letter gray. Change the color when the isColorful property// is set to true.map.data.setStyle((feature)=>{letcolor="gray";if(feature.getProperty("isColorful")){color=feature.getProperty("color")asstring;}return/** @type {!google.maps.Data.StyleOptions} */{fillColor:color,strokeColor:color,strokeWeight:2,};});// When the user clicks, set 'isColorful', changing the color of the letters.map.data.addListener("click",(event)=>{event.feature.setProperty("isColorful",true);});// When the user hovers, tempt them to click by outlining the letters.// Call revertStyle() to remove all overrides. This will use the style rules// defined in the function passed to setStyle()map.data.addListener("mouseover",(event)=>{map.data.revertStyle();map.data.overrideStyle(event.feature,{strokeWeight:8});});map.data.addListener("mouseout",(event)=>{map.data.revertStyle();});}declareglobal{interfaceWindow{initMap:()=>void;}}window.initMap=initMap;
Note: Read theguide on using TypeScript and Google Maps.

JavaScript

letmap;functioninitMap(){map=newgoogle.maps.Map(document.getElementById("map"),{zoom:4,center:{lat:-28,lng:137},});// Load GeoJSON.map.data.loadGeoJson("https://storage.googleapis.com/mapsdevsite/json/google.json",);// Color each letter gray. Change the color when the isColorful property// is set to true.map.data.setStyle((feature)=>{letcolor="gray";if(feature.getProperty("isColorful")){color=feature.getProperty("color");}return/** @type {!google.maps.Data.StyleOptions} */{fillColor:color,strokeColor:color,strokeWeight:2,};});// When the user clicks, set 'isColorful', changing the color of the letters.map.data.addListener("click",(event)=>{event.feature.setProperty("isColorful",true);});// When the user hovers, tempt them to click by outlining the letters.// Call revertStyle() to remove all overrides. This will use the style rules// defined in the function passed to setStyle()map.data.addListener("mouseover",(event)=>{map.data.revertStyle();map.data.overrideStyle(event.feature,{strokeWeight:8});});map.data.addListener("mouseout",(event)=>{map.data.revertStyle();});}window.initMap=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>Data Layer: Dynamic Styling</title>    <link rel="stylesheet" type="text/css" href="./style.css" />    <script type="module" src="./index.js"></script>  </head>  <body>    <div></div>    <!--       The `defer` attribute causes the script 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. See      https://developers.google.com/maps/documentation/javascript/load-maps-js-api      for more information.      -->    <script      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"      defer    ></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-layer-data-dynamichttps://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 2025-11-21 UTC.