@macu/google-map-marker-clusterer-js

Display and cluster markers on a map. Inspired by Marker Clusterer Plus.

You will need Google Maps API access through Google Cloud.

Note: Clusters are recalculated at each zoom level, so they can appear to jump around.

Usage

See demo

(Example uses jQuery)

<script defer src="https://maps.googleapis.com/maps/api/js?key=YOUR_KEY&callback=initMap"></script>
<script src="/build/index.js"></script>

<div id="map" style="height:400px;"></div>
<button id="addMarker">Add marker at address</button>

<script>
var app;

function initMap() {
	var demoData = [];

	// Random locations across HRM (initial display)
	var minLat = 44.6148756441958;
	var minLng = -63.72629600600812;
	var maxLat = 44.74121085567042;
	var maxLng = -63.407799778743716;
	for (var i = 0; i < 100; i++) {
		demoData.push({
			id: 'r' + nextMarkerIndex++,
			label: 'Random ' + nextMarkerIndex,
			latlng: [
				minLat + ((maxLat - minLat) * Math.random()),
				minLng + ((maxLng - minLng) * Math.random())
			],
		});
	}

	app = new MarkerClusterer.default(document.getElementById('map'), demoData, {
		onMarkerClick: function(data) {
			// Return content for popup
			return $('<span/>').text(data.label).get(0);
		},
		clusterIcons: [
			// See icons for example at https://github.com/mikesaidani/marker-clusterer-plus
			{min: 0, icon: {url: '/images/m1.png', anchor: new google.maps.Point(26, 26)}},
			{min: 10, icon: {url: '/images/m2.png', anchor: new google.maps.Point(28, 28)}},
			{min: 20, icon: {url: '/images/m3.png', anchor: new google.maps.Point(33, 33)}},
			{min: 30, icon: {url: '/images/m4.png', anchor: new google.maps.Point(39, 39)}},
			{min: 40, icon: {url: '/images/m5.png', anchor: new google.maps.Point(45, 45)}},
		],
		enableDebug: true,
	});
}

$('#addMarker').on('click', function() {
	var address = window.prompt('Enter full address:');

	if (address && address.trim()) {
		MarkerClusterer.geocodeAddress(address, function(latlng) {
			if (latlng) {
				app.addData({
					id: 'a' + Date.now(),
					label: address.trim(),
					latlng: latlng,
				});
				app.setCenter(latlng);
			} else {
				window.alert('Geocoding failed');
			}
		});
	}
});
</script>

Constructor

var app = new MarkerClusterer.default(map, data, config);

Prop	Description
map	Document element or instance of google.maps.Map. The map instance is accessible via markerClusterer.map.
data	Array of {id: <int | string>, latlng: <[<lat>, <lng>] | {lat: <lat>, lng: <lng>} | google.maps.LatLng>} objects. These objects will be passed to the handler you specify in the config when their respective markers are clicked.
config	Optional configuration. See below for options and defaults.

Config object

Prop	Description
clusterRadius	Pixel radius of cluster bounds on map (default 150). A single cluster may encompass points within this radius on the rendered map.
onMarkerClick	Handler called when a marker is clicked; passed the original data element associated with the marker; may return text content or a DOM node to display in a popover.
clusterIcons	Array of {min: <int>, icon: <url | google.maps.Icon | google.maps.Symbol>} (optionally also specifying color, fontSize, and fontWeight, like google.maps.MarkerLabel) specifying cluster icons to render according to cluster size, where min is the minimum cluster size at which the icon applies; ordered from least to greatest minimum cluster size. Alternately, a function may be provided, accepting a cluster size, and returning the config for the associated cluster icon and label. If config.clusterIcons is not passed in, default cluster icons will be rendered.
enableDebug	Enable debug output covering the initialization and rendering cycle (default false).

Static methods

MarkerClusterer.createGoogleMap(mapEl, fullscreenControl = false)

Creates an instance of google.maps.Map using mapEl for the container. fullscreenControl says whether to show a fullscreen option on the map.

MarkerClusterer.defaultIcon(color, strokeWeight, scale)

Returns a circular icon to use in cluster icon config. color should not have transparency, which is added by default. strokeWeight controls the circle's border line thickness. scale scales the size of the circle.

MarkerClusterer.geocodeAddress(address, callback)

Initiates a lookup request to the Google Maps Geocoding API using the given address. callback is a function that will receive null when the address is empty, false when lookup fails, or an instance of google.maps.LatLng. address may also be an array of address parts to be joined with commas, or an object containing any subset of street, city, province or state, country, postcode or zipcode, sent to Google in that order.

Instance methods

Method	Description
app.setData(data)	Replaces the mapped locations.
app.addData(data)	Adds locations to the map. Do not duplicate IDs already on the map.
app.clearData()	Removes all locations from the map.
app.closeInfoWindow()	Closes the marker popover if one is open.
app.setCenter(latlng)	Centers the map on the given location.
app.calcBounds(data)	Returns a bounding box that contains all the given data.
app.zoomToBounds(bounds)	Pans and zooms to the given bounds.
app.zoomToPosition(latlng, callback)	Pans and zooms to the given location. callback is called after markers at the new location are rendered.

Testing

Build, start server, and access http://localhost:8080/demo.html

npm run prod
python -m http.server 8080