add-image.html

<!DOCTYPE html>
<html>
<head>
    <meta charset='utf-8' />
    <title></title>
    <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
    <script src='https://api.tiles.mapbox.com/mapbox-gl-js/v1.13.2/mapbox-gl.js'></script>
    <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v1.13.2/mapbox-gl.css' rel='stylesheet' />
    <style>
        body { margin:0; padding:0; }
        #map { position:absolute; top:0; bottom:0; width:100%; }
    </style>
</head>
<body>

<div id='map'></div>
<script>
//mapboxgl.accessToken = '<your access token here>';
var map = new mapboxgl.Map({
    container: 'map',
    style: 'styles/freetilehosting/positron.json',
    center: [5.1, 52.0],
    zoom: 8    
});

map.on('load', function () {
    map.loadImage('icons/geodan-15.png', (error, image) => {
        if (error) throw error;
        map.addImage('geodan-15', image);
        map.addLayer({        
            "id": "points",
            "type": "symbol",
            "source": {            
                "type": "geojson",
                "data": {
                    "type": "FeatureCollection",
                    "features": [{
                        "type": "Feature",
                        "geometry": {
                            "type": "Point",
                            "coordinates": [4.91320, 52.34227]
                        },
                        "properties": {
                            "title": "Geodan Amsterdam",
                            "icon": "geodan-15"
                        }
                    }, {
                        "type": "Feature",
                        "geometry": {
                            "type": "Point",
                            "coordinates": [5.29969, 51.69176]
                        },
                        "properties": {
                            "title": "Geodan Den Bosch",
                            "icon": "star-11"
                        }
                    }]
                }
            },
            "layout": {                        
                "icon-image": "{icon}",
                "text-field": "{title}",
                "text-font": ["Open Sans Semibold", "Arial Unicode MS Bold"],
                "text-offset": [0, 0.6],
                "text-anchor": "top"
            }
        });
    });
    
});
</script>

</body>
</html>