Adjust a layer's opacity | Mapbox GL JS

Drag the range slider to adjust the opacity of a raster layer on top of a map.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Adjust a layer's opacity</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.0.1/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.0.1/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<style>
.map-overlay {
font: bold 12px/20px 'Helvetica Neue', Arial, Helvetica, sans-serif;
position: absolute;
width: 25%;
top: 0;
left: 0;
padding: 10px;
}
 
.map-overlay .map-overlay-inner {
background-color: #fff;
box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
border-radius: 3px;
padding: 10px;
margin-bottom: 10px;
}
 
.map-overlay label {
display: block;
margin: 0 0 10px;
}
 
.map-overlay input {
background-color: transparent;
display: inline-block;
width: 100%;
position: relative;
margin: 0;
cursor: ew-resize;
}
</style>
 
<div id="map"></div>
 
<div class="map-overlay top">
<div class="map-overlay-inner">
<label>Layer opacity: <span id="slider-value">100%</span></label>
<input id="slider" type="range" min="0" max="100" step="0" value="100">
</div>
</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',
// Choose from Mapbox's core styles, or make your own style with Mapbox Studio
style: 'mapbox://styles/mapbox/light-v11',
center: [-87.6321, 41.8362],
minZoom: 9.5,
maxZoom: 13,
zoom: 9.5
});
 
const slider = document.getElementById('slider');
const sliderValue = document.getElementById('slider-value');
 
map.on('load', () => {
map.addSource('chicago', {
'type': 'raster',
'url': 'mapbox://mapbox.u8yyzaor'
});
map.addLayer({
'id': 'chicago',
'source': 'chicago',
'type': 'raster'
});
 
slider.addEventListener('input', (e) => {
// Adjust the layers opacity. layer here is arbitrary - this could
// be another layer name found in your style or a custom layer
// added on the fly using `addSource`.
map.setPaintProperty(
'chicago',
'raster-opacity',
parseInt(e.target.value, 10) / 100
);
 
// Value indicator
sliderValue.textContent = e.target.value + '%';
});
});
</script>
 
</body>
</html>
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