Visualize population density | Mapbox GL JS

Use a variable binding expression to calculate and display population density.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Visualize population density</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v2.13.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v2.13.0/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
	// TO MAKE THE MAP APPEAR YOU MUST
	// ADD YOUR ACCESS TOKEN FROM
	// https://account.mapbox.com
	mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
const map = new mapboxgl.Map({
container: 'map', // container ID
// Choose from Mapbox's core styles, or make your own style with Mapbox Studio
style: 'mapbox://styles/mapbox/streets-v12', // style URL
center: [30.0222, -1.9596], // starting position [lng, lat]
zoom: 7 // starting zoom
});
 
map.on('load', () => {
map.addSource('rwanda-provinces', {
'type': 'geojson',
'data': 'https://docs.mapbox.com/mapbox-gl-js/assets/rwanda-provinces.geojson'
});
map.addLayer(
{
'id': 'rwanda-provinces',
'type': 'fill',
'source': 'rwanda-provinces',
'layout': {},
'paint': {
'fill-color': [
'let',
'density',
['/', ['get', 'population'], ['get', 'sq-km']],
[
'interpolate',
['linear'],
['zoom'],
8,
[
'interpolate',
['linear'],
['var', 'density'],
274,
['to-color', '#f5e5f3'],
1551,
['to-color', '#8d00ac']
],
10,
[
'interpolate',
['linear'],
['var', 'density'],
274,
['to-color', '#eff3ff'],
1551,
['to-color', '#08519c']
]
]
],
'fill-opacity': 0.7
}
},
'road-label' // Place polygons under labels
);
});
</script>
 
</body>
</html>