Map-GL-Utils (formerly Mapbox-GL-Utils) adds a number of utility functions and syntactic sugar to a Mapbox GL JS or Maplibre GL JS map instance. If you write a lot of interactive map code, you may appreciate the more concise form, and simpler API.

Full documentation: https://stevage.github.io/map-gl-utils

Major features:

• No need to distinguish between paint, layout and other properties.
• All properties can be expressed as camelCase rather than kebab-case.
• Layer operations can act on multiple layers (given by array, regex or filter function), not just one.
• Source types, layer types and property names are incorporated into function names: addGeoJSON(), addCircleLayer(), setCircleRadius(), getTextFont()...
• Adding layers and sources is idempotent: call addLineLayer() multiple times to create, then update the layer.
• Some other convenience functions: show(), hide(), onLoad(), setData(), fontsInUse()
• Better click and hover functions: hoverPointer(), hoverFeatureState(), hoverPopup(), clickLayer()
• Some functions behave better: removeLayer() (not an error if layer doesn't exist), removeSource() (removes attached layers automatically), setFilter() (works on multiple layers at once), setData() clears data if no GeoJSON provided.

Usage

To use without any build process:

<script src="https://unpkg.com/map-gl-utils"></script>

then

U.init(map)

With Webpack etc:

const mapgl = require('maplibre-gl'); // or require('mapbox-gl');
const map = new mapgl.Map({ ... });

// or:
import U from 'map-gl-utils';
U.init(map);

// A small number of methods (eg hoverPopup) require access to the maplibre-gl/mapbox-gl library itself, in order to instantiate other objects.
require('map-gl-utils').init(map, mapgl);

The default distribution is an ES2015 module with no transpiling. If you experience any syntax issues (such as using older JavaScript versions), use the UMD bundle instead:

// Adds U property to map, containing these methods.
require('map-gl-utils/umd').init(map);

If you want to use Flow types:

import type MapGlUtils from 'map-gl-utils/src/index'

Guide

Working with layers

The props object passed when adding a layer can freely mix paint, layout and other properties. Property keys can be specified in camelCase or kebab-case:

map.U.addCircleLayer('trees-circle', 'trees', {
    circleColor: 'green', // paint property
    circleRadius: ['interpolate', ['zoom'], 12, 3, 15, 5], // paint property
    circleSortKey: ['get', 'tree-sort-key'], // layout property
    filter: ['!=', 'type', 'stump'], // other property
});

Almost every method that works with existing layers (eg, show()) can work with multiple layers. There are four ways to specify the layer(s) you want to modify:

• string: map.U.show('trees-label'); map.U.show('trees-circle');
• array of strings: map.U.show(['trees-label', 'trees-circle']);
• regular expression: map.U.show(/^trees-/);
• function that takes a layer, and returns truthy: map.U.show(layer => layer.source === 'trees');

Adding sources

Methods that add sources return an object ("SourceBoundUtils" in this documentation) that can be chained to allow layers to be added to it:

map.U.addGeoJSONSource('properties')
.addCircleLayer('properties-line', { lineWidth: 3 })
.addSymbolLayer('properties-fill', { fillColor: 'hsla(30,30%,60%,0.5)' })

Adding and removing layers

// Conveniently add a line feature, mixing paint, layout and other properties.
// Notice you can use camelCase for all property names.
map.U.addLineLayer('mylines', 'mysource', {
    lineWidth: 3,
    lineCap: 'round',
    minzoom: 11
});

// Also addFillLayer, addFillExtrusionLayer, addRasterLayer, addVideoLayer, addSymbolLayer, addHillshadeLayer, addHeatmapLayer
map.U.addCircleLayer('mycircles', 'mysource', { circleStrokeColor: 'red' });
// if the layer already exists, calling add*Layer simply updates any of the properties
map.U.addCircleLayer('mycircles', 'mysource', { circleStrokeColor: 'red', circleRadius: 4, filter: ['==', 'type', 'active'});


// and of course add the layer "before" another layer if needed:
map.U.addLineLayer('mylayer', 'mysource', { lineColor: 'red' }, 'toplayer');

// removeLayer() doesn't throw errors if the layers don't exist
map.U.removeLayer(['towns','town-labels']);

Adding and removing sources

// Simpler way to create GeoJSON source:
map.U.addGeoJSON('mysource', geojson);

// Or create a GeoJSON source with initially blank data. This is very convenient if you're loading
// the data separately and will call .setData() later.
map.U.addGeoJSON('mysource');

// Simpler ways to create a vector tile source:
map.U.addVector('mysource', 'mapbox://foo.blah');
map.U.addVector('mysource', 'https://example.com/tiles/{z}/{x}/{y}.pbf');

// Additional properties still work
map.U.addVector('mysource', 'https://example.com/tiles/{z}/{x}/{y}.pbf', { maxzoom: 13 });

// There's also addRaster(), addRasterDem(), addImage(), addVideo()
// Calling any of the add* functions simply updates the source definition if it exists already.

// Automatically removes any layers using these sources. Not an error if sources don't exist.
map.U.removeSource(['buildings', 'roads']);

// You can also use the returned object to add layers conveniently:
map.U.addGeoJSON('buildings', 'data/buildings.geojson')
    .addFillExtrusion('buildings-3d', {
        fillExtrusionHeight: 100,
        fillExtrusionColor: 'grey'
    }).addLineLayer('buildings-footprint', {
        lineColor: 'lightblue'
    });

// Replace the source on an existing layer. (Actually removes and re-adds it.)
map.U.setLayerSource('buildings', 'newsource');
map.U.setLayerSource(['buildings-3d', 'buildings-outline]', 'newsource', 'newsourcelayer');

// To change the source layer, pass a third argument, or null to clear it (if switching from vector tiles to geojson)
map.U.setLayerSource('buildings', 'mylocalbuildings', null);

Setting properties and updating data

// Every property has a setXxx() form:
map.U.setTextSize('mylayer', 12);

// And they all work on multiple layers at once:
map.U.setLineWidth(['mylayer', 'mylayer-highlight'], 4);
map.U.setLineOpacity(/^border-/, 0);
map.U.setFillColor(layer => layer.source === 'farms', 'green');

// There's also a more familiar setProperty() form.
map.U.setProperty('mylayer', 'line-width', 3);
// Existing properties aren't touched
map.U.setProperty('mylayer', {
    textSize: 12,
    textColor: 'red'
});

// There's a `get...` version of every function, too.
map.U.getFillColor('water')

// Simpler way to update source data:
map.U.setData('mysource', data);

// you can leave out the data parameter to clear out a GeoJSON source:
map.U.setData('mysource');

// Easier to remember way to turn layers on and off:
map.U.show('mylayer');
map.U.hide('mylayer');
map.U.toggle(['mylayer', 'myotherlayer'], isVisible);

// To avoid name clashes such as with 'raster', you can use a longer form ending
// with either ...Layer() or ...Source()

map.U.addRasterSource('myrastersource', { type: 'raster', url: 'mapbox://mapbox.satellite', tileSize: 256 });
map.U.addRasterLayer('myrasterlayer', 'myrastersource', { rasterSaturation: 0.5 });

Hovering and clicking

// Use the mouse 'finger' cursor when hovering over this layer.
map.U.hoverPointer('mylayer');

// If you pass several layers, it correctly handles moving from one layer to another
// Use the mouse 'finger' cursor when hovering over this layer.
map.U.hoverPointer(['regions-border', 'regions-fill']);

// Sets a "hover" feature-state to be true or false as the mouse moves over features in this layer.
// Requires that features have an `id`.
map.U.hoverFeatureState('mylayer');

// Want to apply the hover feature-state to a different source?
// For instance, you hover over a label, but want to highlight the surrounding boundary.
map.U.hoverFeatureState('town-labels', 'boundaries', 'town-boundaries');

// You can also add additional event handlers:
map.U.hoverFeatureState('mylayer', 'mysource', 'mysourcelayer',
    e => console.log(`Entered ${e.features[0].id}`),
    e => console.log(`Left ${e.oldFeatureid}`);

// Shows a popup when a feature is hovered over or clicked.
// The third argument is an options object, passed to the Popup constructor.
// callback is called as: (feature, popup) => htmlString
// Make sure you passed the mapboxgl library itself when initialising: U.init(map, mapboxgl).
map.U.hoverPopup('mylayer', f => `<h3>${f.properties.Name}</h3> ${f.properties.Description}`, { anchor: 'left' });
map.U.clickPopup('mylayer', f => `<h3>${f.properties.Name}</h3> ${f.properties.Description}`, { maxWidth: 500 });

// clickLayer() is like .on('click)', but can take an array and adds a 'features' member
// to the event, for what got clicked on.
map.U.clickLayer(['towns', 'town-labels'], e => panel.selectedId = e.features[0].id);

// clickOneLayer tests multiple layers in order, firing callback on the first one that
// is hit. The callback is passed { feature, features, layer, event }.
map.U.clickOneLayer(['town-labels', 'state-boundaries'], e => {
    if (e.layer === 'town-labels') {
        setView('town');
        panel.selectedId = e.features[0].id;
    } else if (e.layer === 'state-boundaries') {
        setView('state');
        panel.selectedId = e.features[0].id;
    }
});

// Optionally pass in an extra callback which is fired for clicks that miss all layers:
map.U.clickOneLayer(['town-labels', 'state-boundaries'], e => {...}, e => {
    console.log('Missed everything');
});

// All these functions return an "undo" function that removes the handlers added:
const remove = map.U.hoverPopup('mylayer', showPopupFunc);
//...
remove(); // no more hover popup

Other functions

// Like on('load') but fires immediately (and reliably) any time after map already loaded.
map.U.onLoad(callback);
// returns a promise if no callback:
await map.U.onLoad();

// Gets the layer definition. Mapbox's `getLayer()` has weird paint and layout properties.
const layer = map.U.getLayerStyle('mylayer');

// Resets all other properties to default first. Ignores non-paint, non-layout properties.
map.setLayerStyle('mylayer', {
    lineWidth: 3
});

// properties() converts an object to a layer object accepted by Mapbox-GL-JS
map.addLayer(map.U.properties({
    id: 'mylayer',
    source: 'mysource',
    type: 'line',
    lineWidth: 3,
    lineCap: 'round',
    minzoom: 11,
    filter: ['==', 'status', 'confirmed']
}));

// layerStyle() is flexible, pass as many or as few of id, source, and type (in that order) as you like:
map.U.layerStyle('mylayer', 'mysource', 'line', { ... })
map.U.layerStyle('mylayer', 'mysource', { ... })
map.U.layerStyle('mylayer', { ... })
map.U.layerStyle({ ... })


// Hide/show/toggle all the layers attached to this source
map.U.hideSource('buildings');
map.U.showSource('buildings');
map.U.toggleSource('buildings', true);

// Update several filters at once.
map.U.setFilter(['buildings-fill', 'buildings-outline', 'buildings-label'], [...]);

// Conveniently load an image into the map in one step
map.U.loadImage('marker', '/assets/marker-pin.png');
map.U.loadImage('marker', '/assets/marker-pin@2x.png', { pixelRatio: 2}).then(/* ... */;


// Update the map style's root "transition" property
map.U.setTransition({ delay: 1000, delay: 0});

// Get a list of fonts used in symbol layers with fontsUsed(). Useful for quickly getting some text displaying.
const fonts = map.U.fontsInUse();
map.U.addSymbolLayer('labels', 'mysource', { textFont: fonts[0], textField: '{label}' });

Contrived example

map.U.onload(() => {
    map.U.addGeoJSON('towns');
    map.U.addCircleLayer('small-towns', 'towns', { circleColor: 'green', filter: ['==', 'size', 'small']});
    map.U.addCircleLayer('large-towns', 'towns', {
        circleColor: 'red',
        filter: ['==', 'size', ['large']],
        circleStrokeWidth: ['case', ['to-boolean', ['feature-state', 'hover']], 5, 1]
    );
    map.U.setCircleRadius(['small-towns', 'large-towns'], 12);
    map.U.hoverPointer(['small-towns', 'large-towns']);
    map.U.hoverFeatureState('large-towns');
    // update the source layer when data is available
    d3.json('http://example.com/towns.json', data => map.U.setData('towns', data));
});

Credits

Map-GL-Utils was written by, and maintained, by Steve Bennett, a freelance map developer.

Documentation built with documentation.js.

Packaging uses rollup.js and Babel.

Flow is used internally, including types from Mapbox GL JS.

Tests are run using Jest.