MapLibre Layer Switcher

This is a layer switcher component for MapLibre GL JS, which is based on the Mapbox layer switcher by @russss. Layers are selected by the string prefix of the layer name.

This package also includes a modified URL hash component which allows a compact representation of the enabled layers to be added to the URL hash.

Use

These steps assume you're using Webpack with css-loader. First, import the layer switcher component and the CSS:

import '@joeyeschner/maplibre-layer-switcher/layerswitcher.css'
import LayerSwitcher from '@joeyeschner/maplibre-layer-switcher';

Now define your layers as an object mapping the layer name to the prefix of the MapLibre GL layers you want to switch. We also define a list of layers which will be initially enabled:

const layers = {
	Power: 'power_',
	'Solar Generation': 'heatmap_',
	Labels: 'place_',
};

const layers_enabled = ['Power', 'Labels'];
const layer_switcher = new LayerSwitcher(layers, layers_enabled);

Adding the layer switcher to the map after it's been initialised will result in the hidden layers being briefly shown. To avoid this, we need to load the style into JS first (I usually bundle it with the rest of my JS), and call the setInitialVisibility method on the loaded style object.

const style = //...load map style JSON into an object
layer_switcher.setInitialVisibility(style);

Now we can instantiate our map and add the layer switcher to it:

const map = new maplibregl.Map({style: style, container: 'map'});
map.addControl(layer_switcher, 'top-right');

URL Hash

To include layers in the URL hash, first import and create the URLHash object, passing in your LayerSwitcher:

import URLHash from '@joeyeschner/maplibre-layer-switcher/urlhash';
// ...
const url_hash = new URLHash(layer_switcher);

When creating the map, you need to call url_hash.init, passing in your default map options. The URLHash class will update the zoom and center options if they're provided in the URL hash. Then call url_hash.enable on the map:

var map = new maplibregl.Map(url_hash.init({
	container: 'map',
	style: style,
	minZoom: 2,
	maxZoom: 17.9,
	center: [12, 26],
}));

url_hash.enable(map);