D3 Examples - Historical Transparency MapBox workshop example

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<!DOCTYPE html>
//Lines 4 - 51 Set up the map and the style.
//Lines 53 - 60 Insert the map and the Layer Opacity info box. 
//Lines 63 -73 Pull in your specific map data from MapBox. Line 67 is your you would insert the style from your Mapbox account.
<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' />
    <script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.49.0/mapbox-gl.js'></script>
    <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.49.0/mapbox-gl.css' rel='stylesheet' />
    <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, 0.20);
    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>
  //this is the default access token. You can customize with your own from your Mapbox account.
mapboxgl.accessToken = 'pk.eyJ1IjoiYW5keS1ydXRrb3dza2kiLCJhIjoiWDJRMFVUWSJ9.iHl6Cf0M79wmHQlfP6Bk8Q';
var map = new mapboxgl.Map({
    container: 'map',
   //Insert your Mapbox style in the next line.
  style: 'mapbox://styles/andy-rutkowski/cjmyg19qb2t712rmq2pvldq00',
center: [-118.268790, 33.968554],
    minZoom: 9.5,
    maxZoom: 13,
    zoom: 9.5
});
​
var slider = document.getElementById('slider');
var sliderValue = document.getElementById('slider-value');
​
map.on('load', function() {
​
    map.addLayer({
        "id": "HOLC1939",
        "source": {
            "type": "raster",
            "url": "mapbox://andy-rutkowski.a0p1p0hr"
        },
        "type": "raster"
    });
​
    slider.addEventListener('input', function(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('HOLC1939', 'raster-opacity', parseInt(e.target.value, 10) / 100);
​
        // Value indicator
        sliderValue.textContent = e.target.value + '%';
    });
});
</script>
​
</body>
</html>
​
    