Improve icon-sprite-webgl example to include hit detection

examples/icon-sprite-webgl.html

@@ -18,3 +18,4 @@ cloak:
     value: Your Mapbox access token from https://mapbox.com/ here
 ---
 <div id="map" class="map"></div>
+<div>Current sighting: <span id="info"></span></div>

examples/icon-sprite-webgl.js

@@ -103,7 +103,7 @@ function loadData() {
 
 loadData();
 
-new Map({
+const map = new Map({
   layers: [
     new TileLayer({
       source: new TileJSON({
@@ -121,3 +121,18 @@ new Map({
     zoom: 2
   })
 });
+
+const info = document.getElementById('info');
+map.on('pointermove', function(evt) {
+  if (map.getView().getInteracting()) {
+    return;
+  }
+  const pixel = evt.pixel;
+  info.innerText = '';
+  map.forEachFeatureAtPixel(pixel, function(feature) {
+    const datetime = feature.get('datetime');
+    const duration = feature.get('duration');
+    const shape = feature.get('shape');
+    info.innerText = 'On ' + datetime + ', lasted ' + duration + ' seconds and had a "' + shape + '" shape.';
+  });
+});