Custom Marker Clustering

This example shows how to use a custom Renderer with MarkerClusterer to customize the appearance of cluster markers.

Read the documentation.

TypeScript

import { MarkerClusterer, ClusterStats } from '@googlemaps/markerclusterer';

async function init() {
    // Request needed libraries.
    const [{ InfoWindow }, { AdvancedMarkerElement, PinElement }] =
        await Promise.all([
            google.maps.importLibrary('maps'),
            google.maps.importLibrary('marker'),
        ]);

    await customElements.whenDefined('gmp-map');

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

    const infoWindow = new InfoWindow({
        content: '',
        disableAutoPan: true,
    });

    // Create an array of alphabetical characters used to label the markers.
    const labels = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

    // Add some markers to the map.
    const markers = locations.map((position, i) => {
        const label = labels[i % labels.length];
        const pinGlyph = new PinElement({
            glyphText: label,
            glyphColor: 'white',
        });

        const marker = new AdvancedMarkerElement({
            position,
            content: pinGlyph,
            gmpClickable: true,
        });

        marker.addEventListener('gmp-click', () => {
            const content = document.createElement('div');
            content.textContent = `${String(position.lat)}, ${String(position.lng)}`;
            infoWindow.setContent(content);

            infoWindow.open({
                anchor: marker,
                map: innerMap,
            });
        });
        return marker;
    });

    // Customize the cluster icons using a custom Renderer
    const renderer = {
        render: (
            {
                count,
                position,
            }: { count: number; position: google.maps.LatLng },
            stats: ClusterStats
        ) => {
            // Change color based on the number of markers in the cluster relative to the mean
            const isLargeCluster =
                count > Math.max(10, stats.clusters.markers.mean);
            const clusterClass = isLargeCluster
                ? 'large-cluster'
                : 'small-cluster';

            // Build the HTML content for the Advanced Marker
            const content = document.createElement('div');
            content.classList.add('custom-cluster-icon', clusterClass);
            content.textContent = String(count);

            return new AdvancedMarkerElement({
                position,
                content,
                // Adjust zIndex to be above other markers
                zIndex: 1000 + count,
            });
        },
    };

    // Add a marker clusterer to manage the markers.
    new MarkerClusterer({ markers, map: innerMap, renderer });
}

const locations = [
    { lat: -31.56391, lng: 147.154312 },
    { lat: -33.718234, lng: 150.363181 },
    { lat: -33.727111, lng: 150.371124 },
    { lat: -33.848588, lng: 151.209834 },
    { lat: -33.851702, lng: 151.216968 },
    { lat: -34.671264, lng: 150.863657 },
    { lat: -35.304724, lng: 148.662905 },
    { lat: -36.817685, lng: 175.699196 },
    { lat: -36.828611, lng: 175.790222 },
    { lat: -37.75, lng: 145.116667 },
    { lat: -37.759859, lng: 145.128708 },
    { lat: -37.765015, lng: 145.133858 },
    { lat: -37.770104, lng: 145.143299 },
    { lat: -37.7737, lng: 145.145187 },
    { lat: -37.774785, lng: 145.137978 },
    { lat: -37.819616, lng: 144.968119 },
    { lat: -38.330766, lng: 144.695692 },
    { lat: -39.927193, lng: 175.053218 },
    { lat: -41.330162, lng: 174.865694 },
    { lat: -42.734358, lng: 147.439506 },
    { lat: -42.734358, lng: 147.501315 },
    { lat: -42.735258, lng: 147.438 },
    { lat: -43.999792, lng: 170.463352 },
];

void init();

JavaScript

import { MarkerClusterer } from '@googlemaps/markerclusterer';

async function init() {
    // Request needed libraries.
    const [{ InfoWindow }, { AdvancedMarkerElement, PinElement }] =
        await Promise.all([
            google.maps.importLibrary('maps'),
            google.maps.importLibrary('marker'),
        ]);

    await customElements.whenDefined('gmp-map');

    const mapElement = document.querySelector('gmp-map');
    const innerMap = mapElement.innerMap;

    const infoWindow = new InfoWindow({
        content: '',
        disableAutoPan: true,
    });

    // Create an array of alphabetical characters used to label the markers.
    const labels = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

    // Add some markers to the map.
    const markers = locations.map((position, i) => {
        const label = labels[i % labels.length];
        const pinGlyph = new PinElement({
            glyphText: label,
            glyphColor: 'white',
        });

        const marker = new AdvancedMarkerElement({
            position,
            content: pinGlyph,
            gmpClickable: true,
        });

        marker.addEventListener('gmp-click', () => {
            const content = document.createElement('div');
            content.textContent = `${String(position.lat)}, ${String(position.lng)}`;
            infoWindow.setContent(content);

            infoWindow.open({
                anchor: marker,
                map: innerMap,
            });
        });
        return marker;
    });

    // Customize the cluster icons using a custom Renderer
    const renderer = {
        render: ({ count, position }, stats) => {
            // Change color based on the number of markers in the cluster relative to the mean
            const isLargeCluster =
                count > Math.max(10, stats.clusters.markers.mean);
            const clusterClass = isLargeCluster
                ? 'large-cluster'
                : 'small-cluster';

            // Build the HTML content for the Advanced Marker
            const content = document.createElement('div');
            content.classList.add('custom-cluster-icon', clusterClass);
            content.textContent = String(count);

            return new AdvancedMarkerElement({
                position,
                content,
                // Adjust zIndex to be above other markers
                zIndex: 1000 + count,
            });
        },
    };

    // Add a marker clusterer to manage the markers.
    new MarkerClusterer({ markers, map: innerMap, renderer });
}

const locations = [
    { lat: -31.56391, lng: 147.154312 },
    { lat: -33.718234, lng: 150.363181 },
    { lat: -33.727111, lng: 150.371124 },
    { lat: -33.848588, lng: 151.209834 },
    { lat: -33.851702, lng: 151.216968 },
    { lat: -34.671264, lng: 150.863657 },
    { lat: -35.304724, lng: 148.662905 },
    { lat: -36.817685, lng: 175.699196 },
    { lat: -36.828611, lng: 175.790222 },
    { lat: -37.75, lng: 145.116667 },
    { lat: -37.759859, lng: 145.128708 },
    { lat: -37.765015, lng: 145.133858 },
    { lat: -37.770104, lng: 145.143299 },
    { lat: -37.7737, lng: 145.145187 },
    { lat: -37.774785, lng: 145.137978 },
    { lat: -37.819616, lng: 144.968119 },
    { lat: -38.330766, lng: 144.695692 },
    { lat: -39.927193, lng: 175.053218 },
    { lat: -41.330162, lng: 174.865694 },
    { lat: -42.734358, lng: 147.439506 },
    { lat: -42.734358, lng: 147.501315 },
    { lat: -42.735258, lng: 147.438 },
    { lat: -43.999792, lng: 170.463352 },
];

void init();

CSS

html,
body,
gmp-map {
    height: 100%;
    margin: 0;
    padding: 0;
}

.custom-cluster-icon {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    border: 2px solid white;
    display: flex;
    justify-content: center;
    align-items: center;
    color: white;
    font-weight: bold;
    font-size: 14px;
    font-family: sans-serif;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
}

.large-cluster {
    background-color: #ff0000;
}

.small-cluster {
    background-color: #0000ff;
}

HTML

<html>
    <head>
        <title>marker-clustering-custom</title>

        <link rel="stylesheet" type="text/css" href="./style.css" />
        <script type="module" src="./index.js"></script>
        <script>
            // prettier-ignore
            (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: "GOOGLE_MAPS_API_KEY"
            });
        </script>
    </head>
    <body>
        <gmp-map
            center="-28.024, 140.887"
            zoom="3"
            map-id="DEMO_MAP_ID"></gmp-map>
    </body>
</html>

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. You will also need a Google Maps API key.

The following commands clone the repository, install dependencies, and copy the environment file. 

  git clone https://github.com/googlemaps-samples/js-api-samples.git
  cd js-api-samples
  npm i
  cp .env.template .env

Once you copy the environment file, make sure to open the .env file and replace <Insert your own development API key here> with your actual API key before starting the sample. 

  cd samples/marker-clustering-custom
  npm start