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/v3.3.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.3.0/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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