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;
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;
/** 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>
<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 id="map"></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>
Git and Node.js are required to run this sample locally. Follow theseinstructionsto install Node.js and NPM. The following commands clone, install dependencies and start the sample application.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis example demonstrates dynamic styling of KML feature objects on a map using a data layer.\u003c/p\u003e\n"],["\u003cp\u003eUsers can hover over features to highlight them with a thicker outline and click to change their color.\u003c/p\u003e\n"],["\u003cp\u003eThe sample utilizes GeoJSON data to display features and allows for customization of fill, stroke, and stroke weight.\u003c/p\u003e\n"],["\u003cp\u003eCode snippets are provided in TypeScript and JavaScript, along with HTML and CSS for implementation.\u003c/p\u003e\n"]]],["The code dynamically styles map features from a GeoJSON data source. Initially, all features are gray. Clicking a feature sets its `isColorful` property to true, updating its color to a specified value. Hovering over a feature temporarily overrides its style to add a thicker outline, tempting the user to click. Moving the mouse off the feature removes this outline, reverting to the previous style. These styles are set and managed using the `map.data.setStyle` and `map.data.overrideStyle` functions.\n"],null,["This example uses a data layer to dynamically change the appearance of some [KML\nfeature objects](/maps/documentation/javascript/kmllayer#kml_feature_details)\nwhen the user hovers over or clicks them.\n\nRead the\n[documentation](/maps/documentation/javascript/datalayer#change_appearance_dynamically). \n\nTypeScript \n\n```typescript\nlet map: google.maps.Map;\n\nfunction initMap(): void {\n map = new google.maps.Map(document.getElementById(\"map\") as HTMLElement, {\n zoom: 4,\n center: { lat: -28, lng: 137 },\n });\n\n // Load GeoJSON.\n map.data.loadGeoJson(\n \"https://storage.googleapis.com/mapsdevsite/json/google.json\"\n );\n\n // Color each letter gray. Change the color when the isColorful property\n // is set to true.\n map.data.setStyle((feature) =\u003e {\n let color = \"gray\";\n\n if (feature.getProperty(\"isColorful\")) {\n color = feature.getProperty(\"color\") as string;\n }\n return /** @type {!google.maps.Data.StyleOptions} */ {\n fillColor: color,\n strokeColor: color,\n strokeWeight: 2,\n };\n });\n\n // When the user clicks, set 'isColorful', changing the color of the letters.\n map.data.addListener(\"click\", (event) =\u003e {\n event.feature.setProperty(\"isColorful\", true);\n });\n\n // When the user hovers, tempt them to click by outlining the letters.\n // Call revertStyle() to remove all overrides. This will use the style rules\n // defined in the function passed to setStyle()\n map.data.addListener(\"mouseover\", (event) =\u003e {\n map.data.revertStyle();\n map.data.overrideStyle(event.feature, { strokeWeight: 8 });\n });\n\n map.data.addListener(\"mouseout\", (event) =\u003e {\n map.data.revertStyle();\n });\n}\n\ndeclare global {\n interface Window {\n initMap: () =\u003e void;\n }\n}\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/samples/layer-data-dynamic/index.ts#L8-L61\n```\n| **Note:** Read the [guide](/maps/documentation/javascript/using-typescript) on using TypeScript and Google Maps.\n\nJavaScript \n\n```javascript\nlet map;\n\nfunction initMap() {\n map = new google.maps.Map(document.getElementById(\"map\"), {\n zoom: 4,\n center: { lat: -28, lng: 137 },\n });\n // Load GeoJSON.\n map.data.loadGeoJson(\n \"https://storage.googleapis.com/mapsdevsite/json/google.json\",\n );\n // Color each letter gray. Change the color when the isColorful property\n // is set to true.\n map.data.setStyle((feature) =\u003e {\n let color = \"gray\";\n\n if (feature.getProperty(\"isColorful\")) {\n color = feature.getProperty(\"color\");\n }\n return /** @type {!google.maps.Data.StyleOptions} */ {\n fillColor: color,\n strokeColor: color,\n strokeWeight: 2,\n };\n });\n // When the user clicks, set 'isColorful', changing the color of the letters.\n map.data.addListener(\"click\", (event) =\u003e {\n event.feature.setProperty(\"isColorful\", true);\n });\n // When the user hovers, tempt them to click by outlining the letters.\n // Call revertStyle() to remove all overrides. This will use the style rules\n // defined in the function passed to setStyle()\n map.data.addListener(\"mouseover\", (event) =\u003e {\n map.data.revertStyle();\n map.data.overrideStyle(event.feature, { strokeWeight: 8 });\n });\n map.data.addListener(\"mouseout\", (event) =\u003e {\n map.data.revertStyle();\n });\n}\n\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/layer-data-dynamic/docs/index.js#L7-L50\n```\n| **Note:** The JavaScript is compiled from the TypeScript snippet.\n\nCSS \n\n```css\n/* \n * Always set the map height explicitly to define the size of the div element\n * that contains the map. \n */\n#map {\n height: 100%;\n}\n\n/* \n * Optional: Makes the sample page fill the window. \n */\nhtml,\nbody {\n height: 100%;\n margin: 0;\n padding: 0;\n}\nhttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/layer-data-dynamic/docs/style.css#L7-L24\n```\n\nHTML \n\n```html\n\u003chtml\u003e\n \u003chead\u003e\n \u003ctitle\u003eData Layer: Dynamic Styling\u003c/title\u003e\n\n \u003clink rel=\"stylesheet\" type=\"text/css\" href=\"./style.css\" /\u003e\n \u003cscript type=\"module\" src=\"./index.js\"\u003e\u003c/script\u003e\n \u003c/head\u003e\n \u003cbody\u003e\n \u003cdiv id=\"map\"\u003e\u003c/div\u003e\n\n \u003c!-- \n The `defer` attribute causes the script to execute after the full HTML\n document has been parsed. For non-blocking uses, avoiding race conditions,\n and consistent behavior across browsers, consider loading using Promises. See\n https://developers.google.com/maps/documentation/javascript/load-maps-js-api\n for more information.\n --\u003e\n \u003cscript\n src=\"https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly\"\n defer\n \u003e\u003c/script\u003e\n \u003c/body\u003e\n\u003c/html\u003ehttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/layer-data-dynamic/docs/index.html#L8-L30\n```\n\nTry Sample \n[JSFiddle.net](https://jsfiddle.net/gh/get/library/pure/googlemaps/js-samples/tree/master/dist/samples/layer-data-dynamic/jsfiddle) [Google Cloud Shell](https://ssh.cloud.google.com/cloudshell/editor?cloudshell_git_repo=https%3A%2F%2Fgithub.com%2Fgooglemaps%2Fjs-samples&cloudshell_git_branch=sample-layer-data-dynamic&cloudshell_tutorial=cloud_shell_instructions.md&cloudshell_workspace=.)\n\nClone Sample\n\n\nGit and Node.js are required to run this sample locally. Follow these [instructions](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm) to install Node.js and NPM. The following commands clone, install dependencies and start the sample application. \n\n git clone -b sample-layer-data-dynamic https://github.com/googlemaps/js-samples.git\n cd js-samples\n npm i\n npm start\n\n\nOther samples can be tried by switching to any branch beginning with `sample-`\u003cvar translate=\"no\"\u003eSAMPLE_NAME\u003c/var\u003e. \n\n git checkout sample-\u003cvar translate=\"no\"\u003e\u003cspan class=\"devsite-syntax-nx\"\u003eSAMPLE_NAME\u003c/span\u003e\u003c/var\u003e\n npm i\n npm start"]]
